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)

The action of carbamoylcholine (Cchol), NaF and other agonists on the generation of inositol phosphates (IPs) was studied in dog thyroid slices prelabelled with myo-[2-3H]inositol. The stimulation by Cchol (0.1 microM-0.1 mM) of IPs accumulation through activation of a muscarinic receptor [Graff, Mockel, Laurent, Erneux & Dumont (1987) FEBS Lett. 210, 204-210] was pertussis- and cholera-toxin insensitive. Ins(1,4,5)P3, Ins(1,3,4)P3 and InsP4 were generated. NaF (5-20 mM) also increased IPs generation (Graff et al., 1987); this effect was potentiated by AlCl3 (10 microM) and unaffected by pertussis toxin. Although phorbol dibutyrate (5 microM) abolished the cholinergic stimulation of IPs generation (Graff et al., 1987), it did not affect the fluoride-induced response. Cchol and NaF did not require extracellular Ca2+ to exert their effect, and neither KCl-induced membrane depolarization nor ionophore A23187 (10 microM) had any influence on basal IPs levels, or on cholinergic stimulation. However, more stringent Ca2+ depletion with EGTA (0.1 or 1 mM) decreased basal IPs levels as well as the amplitude of the stimulation by Cchol without abolishing it. Dibutyryl cyclic AMP, forskolin, cholera toxin and prostaglandin E1 had no effect on basal IPs levels and did not decrease the response to Cchol. Iodide (4 or 40 microM) also strongly decreased the cholinergic action on IPs, this inhibition being relieved by methimazole (1 mM). Our data suggest that Cchol activates a phospholipase C hydrolysing PtdIns(4,5)P2 in the dog thyroid cell in a cyclic AMP-independent manner. This activation requires no extracellular Ca2+ and depends on a GTP-binding protein insensitive to both cholera toxin and requires no extracellular Ca2+ and depends on a GTP-binding protein insensitive to both cholera toxin and pertussis toxin. The data are consistent with a rapid metabolism of Ins(1,4,5)P3 to Ins(1,3,4)P3 via the Ins(1,4,5)P3 3-kinase pathway, followed by dephosphorylation by a 5-phosphomonoesterase. Indeed, a Ca2+-sensitive InsP3 3-kinase activity was demonstrated in tissue homogenate. Stimulation of protein kinase C and an organified form of iodine inhibit the Cchol-induced IPs generation. The negative feedback of activated protein kinase C could be exerted at the level of the receptor or of the receptor-G-protein interaction.
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PMID:Stimulation of generation of inositol phosphates by carbamoylcholine and its inhibition by phorbol esters and iodide in dog thyroid cells. 255 11

The effects of prostaglandins (PGs) on the induction of alkaline phosphatase (ALP) were investigated in osteoblastic clone MC3T3-E1 cells cultured in serum-free medium. Prostaglandin E2 (PGE2) stimulated ALP activity in the cells in a dose-dependent fashion with a maximal effect which was about twice that in the control cells at concentrations of 100-500 ng/ml. Actinomycin D and cycloheximide inhibited the stimulative effect of PGE2 on ALP activity in the cells. PGE2-induced and native ALPs in the cells were of the same type as that in adult mouse calvaria, being heat-labile, L-homoarginine- and levamisole-sensitive, and L-phenylalanine-insensitive. Isobutyl methylxanthine (IBMX), a cAMP phosphodiesterase inhibitor, stimulated the inductive effect of PGE2 on ALP activity at 0.1 mM, at which concentration IBMX alone had little effect on the activity. PGE2 also increased the intracellular cAMP content in a dose-dependent fashion with a maximal effect at 100 ng/ml. PGE1, PGF1 alpha, and PGF2 alpha (primary PGs like PGE2) increased the activity. Our present results suggest that PGs stimulate the differentiation of osteoblasts and are involved in bone formation in vivo, as well as in bone resorption.
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PMID:Inductive effects of prostaglandins on alkaline phosphatase in osteoblastic cells, clone MC3T3-E1. 258 42

The effects of interleukin 1, transforming growth factor-beta (coupling factors), prostaglandin E1, and prostaglandin E2 on incorporation of 45Ca2+ and on alkaline phosphatase activity were studied using cultured ROS 17/2.8 cells, one of cell lines derived from rat osteosarcoma. We found that all these factors stimulate both the incorporation of 45Ca2+ and alkaline phosphatase activity of these cells. On the other hand, one of the bone resorption hormones, parathyroid hormone (PTH), suppressed the proliferation of cells and decreased the alkaline phosphatase activity at considerably low concentrations (1 X 10(-12)-1 X 10(-11) M). However, the hormone stimulated the incorporation of 45Ca2+ by these cells in a dose-dependent manner; the maximum stimulation on day 3 was observed at 1 X 10(-7) M and it was approximately 3 times the control value. The data suggest therefore, that the osteoblasts incorporated calcium ions and transported them while bone resorption was occurring. Thus the ROS 17/2.8 cell line appears to be an advantageous experimental system for the study of calcium metabolism of osteoblasts in vitro.
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PMID:[Effects of various factors involved in bone metabolism on 45Ca2+ incorporation and alkaline phosphatase activity of ROS 17/2.8 cells]. 260 4

The effect of several prostaglandins (PGs) on osteoblastic cells was investigated using clone MC3T3-E1 under serum-free conditions. PGA1, A2, B1, and B2 had little effect on intracellular cAMP, alkaline phosphatase (ALP) activity, and DNA synthesis in the cells. At 4-2000 ng/ml, PGE1 among PG analogs tested had a dose-dependent stimulatory effect on ALP activity in the cells, and this effect was amplified by isobutyl methylxanthine. Also, PGE1 strongly augmented the amount of intracellular cAMP over the same concentration range. However, PGE1 had little effect on ornithine decarboxylase activity and DNA synthesis, and at high doses it rather depressed DNA synthesis. Furthermore, PGE1 did not affect the intracellular cGMP level. The effect of PGE1 on the cells closely mimics that of forskolin, suggesting that the PG stimulates the differentiation of the osteoblastic cells predominantly via the stimulation of adenylate cyclase. In contrast with PGE1, PGF2 alpha strongly increased ornithine decarboxylase activity and DNA synthesis in the cells in a dose-related fashion at low concentrations (4-100 ng/ml), at which concentrations it had little effect on the intracellular cAMP or cGMP level and depressed ALP activity. Moreover, PGF2 alpha depressed the stimulatory effect of PGE1 on ALP activity but did not affect the elevation of cAMP level by PGE1. The accumulation of inositol phosphates was greatly increased by PGF2 alpha in the concentration range effective in stimulating DNA synthesis, but was increased little by PGE1, suggesting that PGF2 alpha is a potent stimulator of phosphatidyl inositol turnover in the cells. In addition, A23187, a Ca ionophore, alone did not influence the DNA synthesis, but the effects of tetradecanoyl phorbol acetate, a direct activator of protein kinase C, were very similar to those of PGF2 alpha. Moreover, the stimulation of DNA synthesis or the inhibition of ALP activity by PGF2 alpha was partially counteracted by H-7, a strong inhibitor of protein kinase C. These results suggest that PGF2 alpha stimulates the proliferation of osteoblastic cells predominantly through the phosphatidyl inositol turnover system following in part the activation of protein kinase C. Our data presented here indicate that PGE1 and PGF2 alpha are closely involved in the differentiation and proliferation, respectively, of osteoblasts in vitro and that their action may be mediated by second messengers which differ from each other.
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PMID:Prostaglandin E1 and F2 alpha stimulate differentiation and proliferation, respectively, of clonal osteoblastic MC3T3-E1 cells by different second messengers in vitro. 282 76

L-ascorbic acid at physiological concentrations (10 micrograms/ml) increased alkaline phosphatase activity in the osteoblastlike rat osteosarcoma cell line, UMR-106. The increase was dose-dependent and detectable at 6 hours after the addition of 100 micrograms/ml ascorbic acid to the medium. Treatment of the cells with 100 micrograms/ml ascorbic acid potentiated the response of cAMP to both PTH and PGE1, while cell growth was inhibited. Furthermore, the number of colonies formed by the cells grown in the soft agar was significantly reduced by increasing concentrations of ascorbic acid. These results indicate that ascorbic acid might play some role in the differentiation of osteoblasts.
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PMID:Effects of ascorbic acid on alkaline phosphatase activity and hormone responsiveness in the osteoblastic osteosarcoma cell line UMR-106. 301 92

An ELISA for PGE2 has been developed which is sensitive to concentrations of 0.5 to 20.0 ng PGE2/ml. Mouse monoclonal anti-PGE2 ascites is utilized in a binding competition between the test sample and an adsorbed conjugate of PGE2-BSA. The antibody which remains bound to the solid phase is quantitated colorimetrically by incubation with alkaline phosphatase-conjugated goat anti-mouse IgG followed by incubation with p-nitro-phenylphosphate. PGE1, PGA1, PGA2, PGB2, 6-keto-PGF1 alpha, PGF2 alpha, 13,14-dihydro-15-keto-PGE2, thromboxane B2 and arachidonic acid showed minimal cross-reactivity with the anti-PGE2. The PGE2 ELISA permits the quantitative analysis of large numbers of samples at a fraction of the cost and time required to process a commercial RIA kit. When linked to the appropriate computer software, data collection and analysis can be performed in less than 10 minutes per 96-well plate. Furthermore, the use of an ELISA system eliminates the radioactive and toxic chemical waste generated by RIA methods.
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PMID:An ELISA for PGE2 utilizing monoclonal antibody. 316 99

The aim of this study was to determine the effect of blood coagulation and platelet aggregation on the perfusability of arterioles (19-50 micron) and capillaries in subepicardial and subendocardial ischemic and nonischemic myocardium of anesthetized open-chest rabbits. Fluorescein isothiocynate-dextran (MW 150,000) was injected intravenously to label perfusable myocardial microvessels of rabbits that were subjected to 60 min of coronary artery occlusion. Fluorescent microscopy was used to identify the perfusable vessels and an alkaline phosphatase stain was employed to locate the total microvasculature of the heart. Stereological principles were utilized to determine various morphometric parameters. About 25% of the capillaries were incapable of being perfused but virtually all arterioles were perfusable in occluded myocardium of the control group. Essentially all capillaries and arterioles were perfusable in nonoccluded myocardium. Collagen infusion produced a perfusion defect in 14% of the capillaries and arterioles in nonoccluded myocardium and in 33% of the capillaries and arterioles in occluded myocardium. Heparin, prostaglandin E1 (PGE1), or PGE1 + heparin did not prevent the perfusion defect in capillaries of occluded myocardium. It is concluded that while promotion of blood coagulation and platelet aggregation was able to produce microvessel obstruction, these hemostatic mechanisms were not primarily responsible for the capillary obstruction observed during myocardial ischemia in the rabbit heart.
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PMID:Effect of blood coagulation and platelet aggregation on perfusable capillaries and arterioles in ischemic and nonischemic myocardium. 365 5

Cultured monolayers of dog kidney (MDCK) cells display many features of in vivo epithelia. This work describes the identification of two separate strains of MDCK cell with entirely different properties. Strain I cells form epithelial monolayers which display a high electrical resistance (4.1 k omega . cm-2); the basal short-circuit is small (approx. 0.5 muamp . cm-2) and is stimulated by adrenaline (1 micrometer) prostaglandin E1 (1 micrometer) and arginine vasopressin (2 micrometer) added to the basal bathing solution. Strain II cells form epithelial monolayers of low electrical resistance; the short circuit current is insensitive to adrenaline, prostaglandin E1 and vasopressin. Strain II cells possess measurable activities of alkaline phosphatase and gamma-glutamyl transpeptidase whereas Strain I cells do not. The specific activity of the (Na+ + K+)-ATPase is two-fold greater in Strain II compared with Strain I. The polypeptide composition of the apical membrane differs substantially between the two cell strains as revealed by radio-iodination of external membrane proteins. Monolayer morphology is substantially different between two cell strains. The results are discussed in relation to previous work on MDCK epithelial and the two types of cell monolayer compared with in vivo tubule segments.
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PMID:Identification of two strains of MDCK cells which resemble separate nephron tubule segments. 611 Apr 42

Treatment of the snail Lymnaea acuminata, the vector for the liver flukes Fasciola hepatica and Fasciola gigantica, with two alkylating agents (cyclophosphamide and busulfan) and one thiocarbamide (thiourea) caused reduction in the number of eggs and production of non-viable embryos. All the three drugs caused reduction in the levels of DNA, RNA and protein and the activity of alkaline phosphatase in the gonadal tissues of this snail. There was enhancement in free amino acid levels and activity of acid phosphatase by these drugs. Discontinuation of treatment could not reverse the cytotoxic effects of these drugs. Treatment of sterilized snails with prostaglandin E1 (PGE1), prostaglandin F2 alpha (PGF2 alpha) or hydrogen peroxide not only restored the number of eggs but also caused full embryonic development. Also, there was near total recovery of RNA, DNA and protein levels and small changes in free amino acid levels as well as the activity of alkaline and acid phosphatase. It has been suggested that the prostaglandins play a modulatory role in protein synthesis. The possible therapeutic use of PGE1, PGF2 alpha and H2O2 has been pointed out.
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PMID:Chemosterilization and its reversal in the snail Lymnaea acuminata. 618 61

A procedure was developed to investigate the electrolyte metabolism of human trabecular bone and its regulation in vitro, in particular the influence of prostaglandins. Trabecular bone was prepared from femoral heads of patients who had undergone hip replacement surgery for coxarthrosis. 500 mg samples were incubated in modified EAGLE's minimal essential medium. Net electrolyte movements between bone and incubation medium were measured. During 6 hours of incubation PGE2 caused an increase in the release of calcium and magnesium from bone into incubation medium as compared to controls. The effect of PGE2 was dose-dependent and comparable to that of human parathyroid hormone 1-34 (hPTH 1-34) whereas hPTH 3-34 had no effect. Human calcitonin (hCT) caused a decrease in the release of calcium and magnesium. PGE2 was found to be the most potent prostaglandin. PGE1 and PGF2 alpha had about 50% and PGF1 alpha about 40% of the potency of PGE2. PGA1 and PGA2 had no effect. The effect of PGE2 could be completely inhibited by hCT and was not further enhanced by hPTH 1-34. Magnesium movement was affected in the same way as calcium movement, while phosphate movement and release of alkaline phosphatase and hydroxyproline from bone into incubation medium were not affected by prostaglandins.
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PMID:Influence of prostaglandins on electrolyte metabolism of human trabecular bone in vitro. 659 50


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