Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

IL-8 is a neutrophil-specific chemoattractant and cellular activator which exists in at least three forms, 69, 72, and 77 amino acids. The predominant monocyte product has 72 amino acids, whereas endothelial cells secrete the 77-amino acid form. The 72-amino acid form has been shown to increase intracellular calcium in neutrophils, but the exact biochemical pathways involved in stimulation of these cells is unknown. N-formyl peptide chemoattractants in neutrophils stimulate the formation of phosphatidylinositol-4,5-bisphosphate (PIP2), a reservoir for second messenger molecules and regulator of actin assembly through its association with the actin-binding proteins, profilin, and gelsolin. The present study examined whether IL-8 altered the enzyme which synthesizes PIP2, phosphatidylinositol-4-phosphate (PIP) kinase. Incubation of intact neutrophils with 10 nM IL-8 caused approximately a twofold increase in the activity of the enzyme. All forms of IL-8 stimulated PIP kinase activity in concentrations ranging from 1 to 50 nM, and the dose-response curves exactly correlated with the order of potency of these cytokines for interacting with the IL-8R on the surface of neutrophils. Lineweaver-Burk analysis of the kinetics of PIP kinase assayed in the presence of 0.03 to 0.7 mM ATP showed that 10 nM IL-8 increased the Vmax of the enzyme 38 to 70.5%, with no significant change in the apparent Km for ATP or for PIP. The stimulation of PIP kinase activity could not be explained by decreased degradation of PIP2 by phospholipase C or phosphomonoesterase activity in the membranes isolated from cells treated with IL-8 or by a decrease in the degradation of ATP. The microfilament disrupter, cytochalasin b, inhibited IL-8 induced stimulation of PIP kinase. These findings demonstrate that all forms of IL-8 stimulate PIP kinase in human neutrophils. This event may provide molecular signals to these cells that are necessary to maintain or change the state of microfilament assembly during cellular activation.
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PMID:IL-8 stimulates phosphatidylinositol-4-phosphate kinase in human polymorphonuclear leukocytes. 131 31

Alkaline phosphatase from Streptomyces hygroscopicus strain JA 5999-R 27-158 was purified and characterized. The enzyme was found in the culture filtrate and in the mycelium. The phosphatase was extracted from the mycelium and purified by adsorption to DEAE-cellulose. To separate impurities, the crude enzyme solution was heated and the phosphatase purified by chromatography through CM-Sepharose and Sephadex G 100. The specific activity of the resulting enzyme was 1000 microMol/min/mg at 25 degrees C. The molecular weight determined by SDS gel electrophoresis was found to be 56 000. The Michaelis-Menten constant determined with p-nitrophenylphosphate as substrate was Km = 1.25 X 10(-3) M. Phosphatase activity was dependent on the presence of Ca++ and the maximum activity of enzyme with p-nitrophenylphosphate as substrate was found at pH 9.2. The pI as detected by isoelectric focusing was at pH 5.6. Temperatures from 30 degrees to 75 degrees C did not affect the stability of the enzyme. The alkaline phosphatase exhibited high substrate specificity; of various phosphomonoesters tested, only p-nitrophenylphosphate, methylumbelliferyl-phosphate, phosphoenolpyruvate, ADP, ATP and tyrosine-O-phosphate was hydrolysed. The activity was inhibited by NAF, Na2P2O7 and EDTA. The involvement of the alkaline phosphatase in the regulation of secondary metabolism was discussed.
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PMID:[Metabolism of phosphate-limited Streptomyces cultures. I. Purification and characterization of alkaline phosphatase produced by Streptomyces hygroscopicus]. 653 19

IP-10 is a member of the chemokine family of cytokines and is induced in a variety of cells in response to interferon gamma and lipopolysaccharide. The self-aggregation common to many chemokines, including IP-10, has hindered the identification of a specific IP-10 receptor. Using an IP-10 alkaline phosphatase fusion protein that fortuitously blocks this self-aggregation, we have identified an IP-10 binding site on a variety of cells including endothelial, epithelial, and hematopoietic cells. This binding site has a Kd of 25 nM, is inhibited by recombinant murine or human IP-10, and is dependent on the presence of cell surface heparan sulfate proteoglycans (HSPG). This conclusion is based on the findings that IP-10 binding to cells is: (a) inhibited by heparin and heparan sulfate; (b) sensitive to a 1 M NaCl wash; (c) eliminated by treatment with heparinase and trypsin; and (d) absent on mutant CHO cells that do not express cell surface HSPG. Platelet factor 4 (PF4), but not IL-8, monocyte chemoattractant protein-1, RANTES, monocyte inflammatory protein (MIP)-1 alpha, or MIP-1 beta, can compete effectively with IP-10 for binding to the cell surface. Furthermore, IP-10 shares with PF4 the ability to inhibit endothelial cell proliferation (IC50 = 150 nM). These studies demonstrate specificity in the interaction of chemokines and HSPG, and they define IP-10 and PF4 as a distinct subset of chemokines sharing an HSPG-binding site and angiostatic properties.
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PMID:The IP-10 chemokine binds to a specific cell surface heparan sulfate site shared with platelet factor 4 and inhibits endothelial cell proliferation. 779 Aug 18

Recent evidence suggests that phospholipase A2 (PLA2)-derived lipid mediators may regulate a number of neutrophil responses including degranulation and adhesion. In view of the potential role of PLA2 in stimulus-secretion coupling, we examined the relationship between PLA2 activation and the surface expression of CD11b/CD18 (MAC-1) in human polymorphonuclear leukocytes (hPMNL), including the functional consequences of PLA2 inactivation on MAC-1-dependent adhesion. The selective inhibition of PLA2 by the marine natural products manoalide (MLD) and scalaradial (SLD) blocks [3H]arachidonic acid (AA) release in calcium ionophore A23187-stimulated neutrophils, and also inhibits secretion of specific and azurophilic granule constituents. Additional studies demonstrate that MLD, SLD, and other less potent PLA2 inhibitors such as 4-bromophenacylbromide and nordihydroguiaretic acid inhibit the surface expression of MAC-1 (IC50: MLD, 0.33 microM; SLD, 0.23 microM; 4-bromophenacylbromide, 2.8 microM; NDGA, 3.5 microM) at concentrations similar to those at which they inhibit [3H]AA release. Inhibitors of cyclooxygenase, 5-lipoxygenase, protein kinase C, or calcium channel antagonists have no effect on MAC-1 expression. PLA2 inactivation also prevents MAC-1 up-regulation in hPMNL stimulated with FMLP, IL-8, TNF-alpha, PMA, or platelet activating factor. In FMLP-stimulated hPMNL, under conditions in which no secondary granule constituents are secreted, MAC-1 and alkaline phosphatase up-regulation from intracellular granules is inhibited by MLD and SLD. Functional assays also demonstrate that MLD and SLD block MAC-1-dependent adhesion of activated neutrophils to keyhole limpet hemocyanin at concentrations that block the surface expression of MAC-1. [3H]AA release and MAC-1 expression in MLD and SLD-treated hPMNL could be recovered in the presence of 1 mM hydroxylamine in a time-dependent fashion, consistent with reported data that MLD and SLD inactivate PLA2 through Schiff base formation. In summary, these data emphasize the role of PLA2 as a key regulator of MAC-1 expression in models of neutrophil adhesion.
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PMID:Regulation of CD11b/CD18 expression in human neutrophils by phospholipase A2. 822 53

Interleukin-8 (IL-8) is a polymorphonuclear leukocyte (PMN) chemoattractant and activator which mediates its effects through specific cell-surface receptors. Indirect evidence indicates that guanine nucleotide regulatory proteins (G proteins) are necessary for transmembrane signaling. The present study characterizes IL-8 receptors in isolated PMN membrane fractions and shows direct regulation of these receptors by guanine nucleotides. The binding of [125I]IL-8 to subcellular fractions of PMNs showed specific binding in a low-density membrane fraction containing alkaline phosphatase, but not in primary or secondary granules. The binding of [125I]IL-8 was rapid and reversible. The equilibrium dissociation constant (Kd) of the receptor ranged from 5.0-12.4 nM and there were 1.58-5.90 . 10(10) receptors/mg protein. The dose-response curves for the competitive binding of three different forms of IL-8 to the receptor labeled by [125I]IL-8 corresponded with their ability to produce chemotaxis and granule exocytosis in PMNs. Treatment of membranes with the nonhydrolyzable analogs of GTP, GMP-PNP and GTP gamma S, inhibited the binding of [125I]IL-8. GMP-PNP decreased the affinity of the IL-8 receptor by approx. 2-fold without altering the total receptor number. These findings demonstrate that IL-8 receptors in PMN membranes are of high affinity and are convertible to a low-affinity state in the presence of guanine nucleotides, suggesting a direct role for G proteins in transmembrane signaling by this cytokine.
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PMID:Characterization of interleukin-8 receptors in human neutrophil membranes: regulation by guanine nucleotides. 832 78

Interleukin-8 (IL-8) such as LUCT (lung giant cell carcinoma-derived chemotactic protein), NAP (neutrophil activating protein) and MDNCF (monocyte-derived neutrophil chemotactic factor), and formylmethionyl-leucyl-phenylalanine (fMLP) are well-known chemoattractants for human polymorphonuclear leukocytes (PMNs) and are able to stimulate phosphorylation of 64-kd protein (p64) in these leukocytes. To elucidate the molecular mechanism of PMN activation with chemoattractants, we investigated the phosphorylation process of p64 in an intact cell. 32P-Labeled PMNs were stimulated with LUCT/IL-8, fMLP, leukotriene B4, or C5a, and phosphorylated proteins were analyzed by two-dimensional electrophoresis and autoradiography. A marked phosphorylation of p64 was observed after stimulation. A new spot of phosphorylated p64 (pp64) could be detected on the gel stained with Coomassie Brilliant Blue, indicating that the isoelectric point (pI) of p64 shifted from 5.3 to a more acidic pI by the phosphorylation forming pp64. The spot of pp64 was shown to be dephosphorylated to p64 by treatment with calf intestine alkaline phosphatase. Other proteins having molecular masses 82, 66, 58, 55 and 50 kd were also phosphorylated. The fMLP-stimulated phosphorylation was time-dependent and saturated within 5 min. Maximum stimulation was achieved with 10 nM fMLP. Phosphoamino acid analysis revealed phosphorylation of serine residues in pp64. Staurosporine (100 nM) and W-7 (100 microM) significantly inhibited the phosphorylation of p64, but H-7 slightly inhibited it. H-8 and herbimycin A did not effect phosphorylation. Phorbol myristate acetate was found to stimulate significantly. Protein kinase C did not stimulate the phosphorylation. These data suggest that protein kinase C and calmodulin-like protein are indirectly involved in the phosphorylation of p64 during chemoattractant-activation of PMN.
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PMID:Characterization of a 64-kd protein phosphorylated during chemotactic activation with IL-8 and fMLP of human polymorphonuclear leukocytes. I. Phosphorylation of a 64-kd protein and other proteins. 839 62

Granulocyte colony-stimulating factor (G-CSF) was administered at a dose of 7.5 or 10 micrograms/kg s.c. once daily for 6d (days 1-6) to two groups consisting of eight and six healthy volunteers. The administration of G-CSF resulted in a rapid decrease in neutrophil counts and serum levels of the secondary granule protein, human neutrophil lipocalin (HNL) after 30 min, followed by a recovery and gradual increase within 180 min. The number of circulating neutrophils and plasma and serum levels of neutrophil secondary granule proteins were dramatically elevated on day 2 (1 d after the administration of G-CSF) and stayed so until day 7. The plasma levels of HNL and lactoferrin (LF) showed a biphasic pattern with peaks at day 2 and days 5-7, and remained highly elevated at day 12. The serum levels of HNL and LF increased rapidly (about 8-fold and 6-fold, respectively) on day 2 and stayed elevated until day 7, subsequently returning to baseline levels. At day 5, neutrophil release induced in vitro by f-MLP was significantly enhanced. The cellular contents of HNL and LF were reduced to about 50% of levels before G-CSF administration at day 5. The release of lactoferrin and HNL, but not of myeloperoxidase (MPO), was slightly enhanced after preincubation of isolated normal neutrophils with G-CSF in vitro, but no obvious release of these proteins was observed with G-CSF alone. The administration of G-CSF resulted in a dramatic increase in the alkaline phosphatase (AP) activity in the plasma membrane, with maximal activity occurring at day 5. Furthermore, during administration of G-CSF, TNF-alpha in plasma increased about 25-fold. TNF-alpha started to rise at day 2 and peaked at day 6. After discontinuation of G-CSF the levels of TNF-alpha gradually decreased. The elevated levels of TNF-alpha (tumour necrosis factor-alpha) were temporally correlated to the other signs of neutrophil activation. GM-CSF and IL-8, however, were not detected in plasma. Our data suggest that G-CSF affects the neutrophils not only directly but also indirectly by the induction of the production of other cytokines such as TNF-alpha.
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PMID:The effect of granulocyte colony-stimulating factor (G-CSF) on the degranulation of secondary granule proteins from human neutrophils in vivo may be indirect. 865 73

Sodium Fluoride (NaF) is the only medication so far clinically available with a bone formation stimulating property, through its peculiar mitogenic dose-dependent action on the osteoblast cell line. Bone strength is commensurate to bone mass, and in a condition with fragility fractures, like osteoporosis, it seems logical to restore bone mass without weakening bone strength. However, as with any active drug. NaF therapy requires adhesion to elementary rules if drawbacks are to be prevented. A first mandatory rule is not to prescribe NaF without calcium supplementation, if bone loss at the appendicular skeleton is to be avoided; to prevent this, the availability of monofluorophosphate (MFP), containing the fluoride and calcium salts in the same preparation has enhanced the compliance to calcium supplementation. A second rule is not to give supraphysiological doses of vitamin D, for the same reason. Third, if one wants to avoid a calcium shift from cortical to trabecular bone and osteomalacia, one should use small doses of NaF, of the order of 50 mg/day. With this in mind, the bioavailability of the drug has to be taken into account, particularly its gastrointestinal absorption which is dramatically enhanced if a plain non entericoated (EC) capsule is used, as compared to that of an EC tablet with the same face value. Too much NaF is deleterious to bone, a fact known for years. Already in 1972, it was noted that in all patients receiving 60 mg or more of NEC NaF, daily, morphologically abnormal bone developed and which appeared irregular and contained areas of incompletely mineralized bone. The bone was histologically and microradiographically normal in patients receiving 45 mg or less of NEC NaF/day. Fourth, NaF therapy is contraindicated in renal insufficiency owing to an enhanced retention in the skeleton. NaF is, however, by no means the ideal medication, because its therapeutic window is narrow. It has many bothersome drawbacks, and notably it is irritating for the gastric mucosa, a hazard which may be partly circumvented by the use of an Ec or slow release tablet. Furthermore, peripheral stress fractures may occur, and, in our experience, they were seen in 17% of patients, almost exclusively in females with a low lumbar BMD. Their occurrence should be curtailed by not allowing an increase in alkaline phosphatase activity of more than 50%. This is a relatively benign complication, because no stress fracture degenerated into a complete fracture. In all cases, the stress fractures healed after a transitory drug discontinuation. If there is some concern about cortical bone, NaF therapy may be associated with an antiresorber like estrogens which will prevent any further bone loss, and does not impair the response to NaF. NaF therapy should be reserved for patients suffering chiefly from trabecular osteoporosis and should be avoided in senile osteoporosis, because of a frequently impaired renal function. Currently, we would recommend in clinical practice a daily dose of 50 mg EC-NaF or 150 mg Ca-MFP as the therapy of involutional osteoporosis in women, reserving the dose of 75 mg EC-NAF or 200 mg MFP for males or female patients resistant to lower dose. The therapy should be maintained for 2 to 3 years, or more, according to the bone response, taking into account that patients with the vertebral crush fracture syndrome have lost on average 30%, as compard to the young adult mean.
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PMID:Fluoride therapy of type I osteoporosis. 884 58

We have developed an enzyme-linked immunosorbent assay (ELISA) for the sequential analysis of multiple cytokines in limited volumes of biological fluids, including gingival crevicular fluid (GCF) and fibroblast culture supernatants (CS). GCF and CS samples were assayed for multiple cytokines, including IL-1 beta, IL-6, IL-8, GM-CSF and IFN gamma. Immulon 3 microplates were coated with a monoclonal antibody, and a rabbit polyclonal antibody was used to detect the cytokine of interest. Biological samples (200 microL) were added to an anti-IL-1 beta-coated plate and incubated, and 175 microL of each sample were replicate transferred to an anti-IFN gamma-coated plate containing 25 microL/well of diluent. This was repeated in an identical fashion with sequential replicate transfers to an anti-IL-8-coated and finally an anti-IL-6-coated plate. The cytokine standard was a pooled combination of the recombinant human cytokines that were included in the sequence. The plates were developed using an alkaline phosphatase-conjugated goat anti-rabbit IgG and NPP as the substrate. Individual ELISAs ranged in sensitivity from 30 to 2 pg/0.2 mL, with cross-reactivity between these cytokines of < 1%. Additionally, when the same samples were tested in the sequence ELISA vs. the individual ELISA, there was > 85% correlation between the two assays.
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PMID:Sequential ELISA for cytokine levels in limited volumes of biological fluids. 887 92

Dermatitis herpetiformis (DH) is a chronic subepidermal blistering disease, in which a perivascular cellular infiltrate, composed mainly of CD4+ T lymphocytes together with a varying number of neutrophils and eosinophils, is thought to be important in the pathogenesis of blister formation. The aim of this study was to investigate the potential role of cytokines such as the interleukins IL-4 and IL-5 and to quantify the distribution of T cells as well as their state of activation using alkaline phosphatase-antialkaline phosphatase and reverse transcriptase-polymerase chain reaction (RT-PCR) procedures in seven patients with typical clinical and histological features of DH. A strong extracellular staining with anti-IL-4 monoclonal antibody was detected in the upper dermis with a prevalent perivascular pattern in perilesional areas, whereas in the dermal-epidermal separation sites there was an intense, scattered distribution. IL-5 was intensely expressed, mainly at the intracellular level, by eosinophils and lymphocytes. Concerning RT-PCR, five DH patients showed a strong positive signal for both IL-4 and IL-5 cytokines while two patients showed a faint signal for both IL-4 and IL-5; these last two cases were histologically poor in inflammatory cells. In view of these results, it can be hypothesized that the recruitment of eosinophils and neutrophils in DH may be induced not only by granulocyte macrophage colony-stimulating factor and IL-8 as previously demonstrated, but also by Th2 cytokines as well.
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PMID:Th2-like cytokine activity in dermatitis herpetiformis. 960 68


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