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 effects of the immunosuppressive drug cyclosporin A (CsA) were evaluated on ROS 17/2.8 cells in vitro. ROS cells were treated with CsA (0, 0.5, 1.0, 5.0 micrograms/ml) for 3 days with and without bovine parathyroid hormone (bPTH) (1-34) 10 nM. CsA at 0.5, 1.0, 5.0 micrograms/ml without PTH and at 5.0 micrograms/ml in the presence of PTH significantly inhibited proliferation, as determined by a tetrazolium colorimetric assay. In addition, ROS cell number was significantly reduced at 3 and 4 days with CsA (5.0 micrograms/ml) without affecting cell viability. Incorporation of [3H]-thymidine into DNA was significantly reduced by 3.0 and 5.0 micrograms/ml CsA after 12 and 24 hours exposure. Basal and 1,25-dihydroxyvitamin D3-stimulated alkaline phosphatase levels in confluent ROS cells were reduced (P less than 0.05) with CsA (1.0 and 3.0 microgramS/ml). Pretreatment of ROS 17/2.8 cells with CsA did not alter PTH-stimulated cAMP levels or [125I]-PTHrP binding to ROS cells. CsA treatment of ROS 17/2.8 cells induced a spindle-shaped appearance with loss of attachment in confluent cultures. When ROS cells were cultured in CsA-containing media, cellular attachment at 6 and 12 hours was reduced (P less than 0.05) compared with untreated ROS cells. These findings indicate that CsA was capable of inhibiting proliferation, cell number, mitogenesis, alkaline phosphatase levels, and cell attachment of ROS cells without affecting PTH binding or cAMP levels. This direct effect of CsA on osteoblasts may be important in changes of bone remodeling observed in CsA-treated humans and animals.
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PMID:Effects of cyclosporin A on rat osteoblasts (ROS 17/2.8 cells) in vitro. 133 Feb 39

Saccharomyces cerevisiae contains an amphiphilic cAMP-binding glycoprotein at the outer face of the plasma membrane (M(r) = 54,000). It is converted to a hydrophilic form by treatment with glycosyl-phosphatidylinositol-specific phospholipases C and D (GPI-PLC/D), suggesting membrane anchorage by a covalently bound glycolipid. Determination of the constituents of the purified anchor by gas-liquid chromatography and amino acid analysis reveals the presence of glycerol, myo-inositol, glucosamine, galactose, mannose, ethanolamine, and asparagine (as the carboxyl-terminal amino acid of the Pronase-digested protein to which the anchor is attached). Complementary results are obtained by metabolic labeling, indicating that fatty acids and phosphorus are additional anchor constituents. The phosphorus is resistant to alkaline phosphatase, whereas approximately half is lost from the protein after treatment with GPI-PLD or nitrous acid, and all is removed by aqueous HF indicating the presence of two phosphodiester bonds. Inhibition of N-glycosylation by tunicamycin or removal of protein-bound glycan chains by N-glycanase or Pronase does not abolish radiolabeling of the anchor structure by any of the above compounds. Analysis of the products obtained after sequential enzymic and chemical degradation of the anchor agrees with the arrangement of constituents in GPIs from higher eucaryotes. Evidence for anchorage of the yeast cAMP-binding protein by a GPI anchor is strengthened additionally by the reactivity of the GPI-PLC-cleaved anchor with antibodies directed against the cross-reacting determinant of trypanosomal variant surface glycoproteins.
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PMID:The cAMP-binding ectoprotein from Saccharomyces cerevisiae is membrane-anchored by glycosyl-phosphatidylinositol. 133 92

Fragments of cancellous and cortical bone from human maxilla and mandible were cultured by the explant technique. Cells isolated by trypsinization of primary cultures were characterized as osteoblasts on the basis of intracellular alkaline phosphatase activity, the constituents of the extracellular matrix, and response to human parathormone (PTH). In culture, the osteoblasts often gave rise to superposed clumps of large cells whose cytoplasm contained endoplasmic reticulum, numerous mitochondria, vacuoles, and a dense network of intermediate filaments, often at the level of the plasma membrane. In the presence of vitamin C and 1,25-dihydroxyvitamin D3, the osteoblasts produced an extracellular matrix composed of collagen type I and various non-collagenous proteins, including osteocalcin. Biochemical test results were comparable to those reported for osteoblasts of other origins (rat calvaria, human iliac crest), and namely elevated intracellular alkaline phosphatase activity and cAMP accumulation in response to stimulation by human PTH (1-34). Osteoblasts isolated in this manner were cultured in the presence of pure titanium disks to determine the effects of exposure to this metal. Electron microscopy revealed few significant differences in cell growth and specific enzyme activity compared to control osteoblasts grown on plastic dishes, reflecting the excellent biologic and biochemical relationship between the osteoblasts and pure titanium. This experimental system thus appears suitable for biocompatibility studies, and in particular, evaluation of dental implants.
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PMID:Characterization of endosteal osteoblasts isolated from human maxilla and mandible: an experimental system for biocompatibility tests. 136 48

Pulsatile TSH secretion has been described in man. We investigated the effect of discontinuous TSH stimulation on FRTL-5 thyroid cells. FRTL-5 monolayers were pulsed with TSH in 4 h incubation periods with alternate 4 h TSH-free intervals, or continuously incubated with TSH. The cAMP production of cells was measured in the supernatant of monolayers. Expression of a nuclear proliferation antigen in FRTL-5 monolayers was determined by a monoclonal antibody (Ki-67) using the alkaline phosphatase-anti-alkaline-phosphatase staining method. The TSH concentration in the stimulation series ranged from 0.01 to 1.0 U/l medium. Rhythmic cAMP production was observed in both discontinuous and continuous stimulation. With discontinuous stimulation cAMP production peaked after about 24 and 48 h, while in the continuous presence of TSH peaks were observed at 32-40 and 48 h. At all TSH concentrations the effect of discontinuous stimulation was higher than in continuously stimulated cultures. The discontinuous incubation stimulated nuclear proliferation antigen expression of FRTL-5 more intensely and there was a positive correlation with TSH concentration. We conclude that the rhythmic pattern of cAMP production after TSH stimulation is independent of the TSH pulse. The amplitude of stimulation and proliferation of FRTL-5, however, is increased by discontinuous TSH application.
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PMID:Discontinuous and continuous stimulation of FRTL-5 thyroid cells with bTSH cause different cAMP and nuclear proliferation antigen responses. 137

The voltage-dependent Na+ channel of the brain is a good substrate for phosphorylation by the cAMP-dependent protein kinase (protein kinase A, or PKA), but the physiological effects of PKA on Na+ channels are poorly documented. We studied modulation by PKA of voltage-dependent Na+ channels expressed in Xenopus oocytes injected with RNA coding for the alpha-subunit of the channel protein (rat brain type IIA and its variant VA200), using the two electrode voltage-clamp technique. Intracellularly injected cAMP or catalytic subunit of PKA, or extracellularly applied forskolin, inhibited the Na+ current by 20-30%. The effect of cAMP was attenuated by prior injection of PKA inhibitors. Injection of small doses of protein phosphatase 2A increased the Na+ current by 10%, whereas larger doses of protein phosphatase 1 and alkaline phosphatase were without effect. The inhibition by PKA showed little voltage dependence, being only slightly stronger at holding potentials at which the availability of the channels was reduced. The voltage dependence of activation and inactivation processes was not altered by cAMP. Similar effects were exerted by forskolin and cAMP on the Na+ channels expressed after the injection of heterologous (total) RNA from rat brain. Thus, PKA modulates the Na+ channel by a mechanism that does not involve major changes in the voltage dependency of the current and is exerted on the channel-forming alpha-subunit.
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PMID:Protein kinase A reduces voltage-dependent Na+ current in Xenopus oocytes. 138 76

The phenotype of Escherichia coli appR pleiotropic mutants has been compared with that of mutants in the katF gene, which lies in the same region and controls expression of catalase HPII (katE) and exonuclease III (xth). All the described characters of appR mutants--reduced pH 2.5 acid phosphatase level, overexpression of alkaline phosphatase and ability of crp or cya mutants to utilize some CAP + cAMP-dependent carbon sources--were reproduced by a katF:: Tn10 insertion. In all cases, the wild-type phenotype was restored by the presence of a plasmid-borne katF+ gene. Conversely, spontaneous appR mutants were hypersensitive to H2O2 to the same degree as katF mutants. We conclude that the appR gene is identical to katF, which encodes a putative new sigma factor (Mulvey and Loewen, 1989).
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PMID:Are appR and katF the same Escherichia coli gene encoding a new sigma transcription initiation factor? 164 76

Ascites sarcoma 180 (S180A) is a transplantable tumor maintained in ddY mice. In the tumor-bearing mice, the plasma Ca, Pi and acid phosphatase levels increased and the plasma alkaline phosphatase levels decreased. The elevation of plasma Pi levels is unusual in humoral hypercalcemia of malignancy (HHM). To characterize the pathogenesis of HHM in the animals, the biological activities in the serum-free conditioned media (CM) of S180A cell cultures were examined. The S180A CM stimulated bone resorption dose dependently and showed TGF-like, IL-1-like and mitogenic activity. Unlike parathyroid hormone (PTH), the factor(s) failed to stimulate cAMP production by either UMR 106-01 cells or neonatal mouse calvaria at concentrations that stimulate bone resorption. Also, the factor(s) stimulated proliferation of UMR 106-01 cells concomitant with a slight increase in intracellular calcium levels. These results indicate that S180A cells produce a factor(s) responsible for bone resorption which is apparently different from PTH-like activity.
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PMID:Ascites sarcoma 180, an animal model of humoral hypercalcemia of malignancy, produces a factor(s) exhibiting potent bone-resorbing activity without any parathyroid hormone-like activity. 165 Nov 37

We investigated the effects of hypergravity on DNA synthesis and alkaline phosphatase (ALP) activity in cloned osteoblast-like cells, MC3T3-E1. Hypergravity (5 x g) stimulated DNA synthesis in these cells in a time-dependent manner and increased it approximately up to 150% of that of the control (1 x g). 12-O-Tetra-decanoylphorbol-13-acetate (TPA), a protein kinase C activator, and insulin-like growth factor I (IGF-I) enhanced DNA synthesis additively with hypergravity (5 x g). An increase in ALP activity induced by 10% fetal calf serum (FCS) was suppressed by hypergravity (2 x g, 5 x g). Five x g completely suppressed the increase in ALP activity. TPA and hypergravity (2 x g) suppressed the increase in ALP activity induced by FCS additively. Hypergravity (5 x g) showed no significant effect on cAMP nor cGMP production in these cells, but increased prostaglandin E2 (PGE2) production. Exogenous PGE2 stimulated DNA synthesis in these cells but had little effect on 10% FCS-induced ALP activity. These results suggest that hypergravity stimulates proliferation but suppresses differentiation of osteoblast-like cells through a pathway independent of the activation of protein kinase C and the production of cyclic nucleotides, and that hypergravity and IGF-I stimulate proliferation of these cells through an independent signal transduction pathway. Moreover, our data strongly suggest that PGE2 mediates the signalling of hypergravity on the proliferation of osteoblast-like cells.
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PMID:Effects of hypergravity on proliferation and differentiation of osteoblast-like cells. 165 Nov 38

A series of stromal cell lines derived from mouse bone marrow, representing subpopulations of putative stromal cell types, were examined for the expression of osteoblastic properties. The effects of dexamethasone and specific inhibitors on alkaline phosphatase activity, cAMP response to bone-seeking hormones, and the ability to mineralize extracellular matrix in vitro as well as collagen typing were used as osteoblastic markers. We found that all stromal cell types examined possess some osteoblastic features but differ in the degree of expression. The data provide support to the hypothesis of a common stem cell for marrow stromal cells.
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PMID:Subpopulations of marrow stromal cells share a variety of osteoblastic markers. 165 28

Clonal osteoblastic cell lines were isolated from neonatal rat calvariae and characterized with regard to a number of features associated with authentic osteoblasts. These included elevated alkaline phosphatase activity (relative to fibroblasts), PTH and PGE2-stimulated increases in cAMP, the predominant synthesis of type 1 collagen, and the production of a mineralized matrix in vitro. By these criteria, five clones with osteoblast-like phenotypes were identified (ROB-C8a, C11, C20, C23, and C26) which varied somewhat in shape, levels of alkaline phosphatase activity, and in responsiveness to PTH and PGE2. C11, C20, and C23 responded to both effector substances, whereas C8a only responded to PTH and C26 only responded strongly to PGE2. Upon further examination, two of the clones (C23 and C26) were also found to exhibit significant muscle myotube formation after reaching confluence, and three of the clones (C8a, C11, and C26) showed marked adipocyte differentiation after treatment with dexamethasone. Overall, these data add further supporting documentation to (1) the suspected ontogenetic relationships of osteoblasts to other connective tissue cells, and (2) the concept that osteoblastic cells associated with neonatal rat calvariae are in various stable stages of differentiation and developmental commitment.
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PMID:Clonal osteogenic cell lines express myogenic and adipocytic developmental potential. 165 29


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