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)

Human placental homogenates and membrane fractions were centrifuged on continuous sucrose density gradients, with or without buoyant density perturbation of plasma-membranes by digitonin, and aliquots of each gradient fraction were assayed for a range of plasma-membrane and intracellular organelle markers, and for specific binding and inactivation of radiolabelled GnRH agonist (GnRHA), Buserelin ([D-Ser(tBu)6] GnRH 1-9 ethylamide). GnRH agonist (GnRHA) binding equilibrated in the same regions of control gradients as the plasma-membrane markers, EGF-receptor and alkaline phosphatase. Moreover, binding of 125I-labelled GnRHA and 125I-labelled chicken GnRH II (ch GnRH II) was enriched in the same regions of the gradients, indicating that both bound to the same membrane fractions. Digitonin pretreatment increased the buoyant density of all three placental plasma-membrane markers to a similar degree. Intracellular organelle markers (and hCG content) equilibrated in different regions of the gradient to placental surface-membranes, and were not perturbed appreciably by digitonin. In contrast, inactivation of 125I-labelled GnRHA was associated largely with the soluble (cytosol) fraction which failed to enter the gradient, and little tracer inactivation was observed in fractions enriched in GnRHA binding activity. Similar results were obtained with fractionated rat pituitary membranes. We conclude that: (a) placental GnRH binding sites do not represent binding of radiolabelled ligand to GnRH-degrading enzymes, (b) degradation of radiolabelled ligand is associated largely with placental cytosol fractions, and (c) GnRH binding activity appears to be associated largely with placental plasma-membranes.
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PMID:Human placental gonadotrophin-releasing hormone (GnRH) binding sites: II. Comparison of binding and inactivation of 125I-labelled GnRH agonist to subcellular fractions following density gradient centrifugation. 133 45

Suckling rats were given urogastrone-epidermal growth factor (EGF: 1,000 micrograms/kg body weight) or vehicle by gavage at one of three stages of development: 8 to 10, 11 to 13 or 14 to 16 days of age. Intubation was carried out at 8-hourly intervals over these periods. Fourteen to 16 h after the last intubation the rats were killed; that is, at 11, 14 and 17 days respectively. Samples of proximal and distal small intestine (SI) were taken for enzyme analysis. Five enzymes were assayed; sucrase, lactase, gamma-glutamyl transferase, alkaline phosphatase and neutral amino-peptidase, and their activities expressed per g protein. Treatment with EGF had no effect on body weight or on the length of the small intestine at any age. The nature of the effects on enzyme activities depended on the specific enzyme concerned, the site within the small intestine and the timing of the treatment. Lactase was increased by EGF at both sites only on day 14, whereas gamma-glutamyl transferase was increased in proximal samples at 11 and 14 days, and in distal samples at 17 days. Nor was the outcome always to increase activity. On day 11 alkaline phosphatase was increased in proximal SI, but decreased in distal SI; and so too was aminopeptidase N decreased in distal SI at 11 days. Sucrase showed no response at all. The pattern is complex. Certainly it does not indicate accelerated functional maturation.
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PMID:Effects of urogastrone-epidermal growth factor and age at administration on five enzymes in the small intestine of suckling rats. 136 15

Osteoblastic cells were cloned by culturing rat calvariae cells in agarose in the presence of TGF-beta and EGF. Two bone cell lines were established by immortalizing such an osteoblastic clonal cell population by the introduction of the avian v-mycOK10 gene in the form of a mouse ecotropic retrovirus. Although originating from the same clonal cell population, the two lines exhibited somewhat differing properties. IRC10/30-myc1 expressed alkaline phosphatase (AP), showed PTH- and PGE2-induced cAMP production, synthesized mainly collagen type I and a minor fraction of type III, and produced mRNA for the bone-specific protein osteocalcin. IRC10/30-myc3 did not express AP, showed no PTH responsiveness, and synthesized only about one-third as much collagen as IRC10/30-myc1 (4 versus 12% of total protein synthesis). However, the cell line IRC10/30-myc3 was induced to synthesize cAMP by PGE2 and produced osteocalcin mRNA. When cultured in vivo in diffusion chambers, both lines proved to be osteogenic. Besides bone, both lines also formed cartilage and fibrous tissue. Thus, by immortalizing a clonal cell population of the osteoblastic phenotype, cell lines expressing varying properties can emerge. Furthermore, the expression of alkaline phosphatase and PTH-inducible adenylate cyclase are not prerequisites for a cell to form bone in vivo. Finally, cells expressing the phenotype of differentiated osteoblasts, including osteocalcin synthesis, still have a multipotential differentiation capacity and form bone and cartilage in vivo.
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PMID:Establishment and characterization of two immortalized cell lines of the osteoblastic lineage. 188 24

Mouse osteoblastic clone MC3T3-E1 was proved as a target cell for retinoic acid (RA) in bone tissues through the demonstration of RA-receptor gene expression by the northern blot analysis. The effect of RA on the cell growth of MC3T3-E1 was repressive for both subconfluent and confluent growth, whereas RA enhancement of alkaline phosphatase expression was observed at the confluent stage. This implies that RA is a regulatory factor leading osteogenesis of the cells after the confluent stage. RA exhibited simultaneously the stage-dependent effects on EGF-dependent mitogenesis: promotive at the subconfluent, but repressive at the confluent stage.
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PMID:Functional modes of retinoic acid in mouse osteoblastic clone MC3T3-E1, proved as a target cell for retinoic acid. 215 37

The effect of matrix components extracted Bovine periodontal ligament (PDL) on cell proliferation and alkaline phosphatase activity of cultured human periodontal ligament fibroblast (HPLF) were examined in order to understand the cell-tissue interaction of periodontal ligament. Bovine PDL tissue was sequentially extracted with 0.05 M Tris HCl buffer, pH 7.4, containing 1M NaCl or 4M GdmCl. After seeding 24 hours, the cultured HPLF were exposed to the extracts for two through eight days. Nine days after seeding, HPLF indicated four times high activity on ALP and 1.6 times the amount of total protein than those of control (without extract), while DNA synthesis increased only 1.2 times. On the contrary, the NaCl extract depressed the ALP activity of HPLF. The GdmCl extract enhanced both the total protein and ALP activity in dose-dependently. The ALP increasing activity of GdmCl extract on HPLF is stable to heat (78 degrees C, 20 min) and collagenase treatment but partially inactivated by trypsin digestion. Since the GdmCl extract also induced colony formation of NRK-49F cell in soft agarose, it was suggested that the extract contain EGF and TGF-beta like factor. Molecular size of this factor was estimated as 20-50Kd using Sepharose CL-6B gel chromatography. Furthermore, this factor from Sepharose CL-6B were separated into two forms by ion exchange CM-Sepharose column chromatography. Purified preparation from reversed phase column chromatography contained 14Kd, 15Kd, 17Kd, 20Kd, 28Kd40Kd, and 46Kd components on SDS-PAGE. This factor may accumulate in extracellular matrix, and may play a role of cell-tissue interaction and homeostasis in periodontal ligament.
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PMID:[Biochemical study on the TGF-beta like growth factor derived from bovine periodontal ligament]. 248 40

A culture system is described in which rat kidney proximal tubule epithelial cells (RPTE) can be prepared with good yield and high viability and grown in culture under serum-free conditions. The cells require EGF, insulin, cholera toxin and either 1% dialyzed serum or a complex of bovine serum albumin with oleic acid (BSA/OA). The cells can be maintained for long periods of time and express several markers for RPTE. The cells have both alkaline phosphatase and gamma-glutamyltransferase activity and respond to parathyroid hormone but not vasopressin. The specific activity of gamma-glutamyltransferase decreases when the cells begin to grow, but increases when they reach confluence. Extracellular calcium plays a role in the induction of gamma-glutamyltransferase in confluent cells. Cells grown in media containing low calcium, i.e. less than 0.4 mM, have reduced specific activity of gamma-glutamyltransferase. Extracellular calcium also alters the morphology of the cells in that cells grown in low calcium are single cells or loose clusters suggesting poor cell-cell contact. When the calcium is raised to 1.0 mM, the cells change their shape and organization to adopt the morphology of cells maintained continuously in 1.0 mM calcium. The cells can be passaged onto plastic surfaces which have been coated with collagen but cannot be subcultured on uncoated or serum coated plastic. This culture system will be a useful model for the investigation of renal carcinogenesis and the role of cell proliferation in that process.
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PMID:Rat kidney proximal tubule cells in defined medium: the roles of cholera toxin, extracellular calcium and serum in cell growth and expression of gamma-glutamyltransferase. 256 95

We have previously reported that the J774A.1 macrophage-like tumor cell line produces two potent monokines which stimulate the growth of osteoblasts and chondrocytes. These growth factors, which have an affinity for heparin-agarose, have been termed HEP I (a 30 Kd PDGF-like molecule) and HEP II (an approximately 20 Kd molecule), respectively, based on their elution profile. Unlike HEP I, HEP II does not stimulate the growth of fibroblasts. Extensive biological and chromatographic studies disclosed that HEP II appears to be a unique bone cell mitogen unlike any known growth factor, including the FGFs, IL-1s, and TNFs, EGF, IGF-I and -II, TGF-beta, beta 2 microglobulin, G-CSF, CSF-1 and GM-CSF. To characterize more fully the effects of the macrophage-derived monokines on osteoblast growth and function, clones were derived from calvaria explant cultures. Two clones, SDFRC-2.05 and SDFRC-3, were developed and found to exhibit osteoblastic characteristics, including high levels of alkaline phosphatase, synthesis of type I but not type III collagen, and an increased intracellular cAMP production in response to PTH. The SDFRC-3 cells exhibited a polygonal morphology like that of the explant-derived cells while SDFRC-2.05 cells exhibited a more fibroblastic morphology. When tested on the explant cultures and clones, HEP I and HEP II were found to stimulate DNA synthesis and increase protein per culture, but decreased alkaline phosphatase activity. Clone SDFRC-3 was found to be more responsive to HEP II than clone SDFRC-2.05. Both monokines were found to be more potent mitogens for bone cells than TGF-beta. HEP II, but not HEP I or TGF-beta, induced a transformation of bone cells from a polygonal to a fibroblastic morphology, suggesting the induction of migration prior to proliferation. Thus, macrophages may be responsible not only for bone repair but also for ensuring the linkage of bone formation to resorption during physiological remodeling.
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PMID:Monokines produced by macrophages stimulate the growth of osteoblasts. 263 Jan 69

Recent techniques have been devised for the culture of bone cells derived from human bone explants. These cells, which are thought to represent several stages in the osteoblast lineage, respond to PTH with an increase in cyclic AMP content, and have high basal alkaline phosphatase activity which is increased on exposure to 1,25-dihydroxyvitamin D3 and decreased by PTH. Such characteristics distinguish these cells from fibroblasts. In this study, we demonstrate that human bone-derived cells also differ from fibroblasts in their growth characteristics. Bone-derived cells proliferated in basal medium supplemented with platelet-poor plasma. The rate of proliferation was enhanced by additional supplementation with platelet-derived growth factor (PDGF), and further increased when a combination of growth factors was added (PDGF, TGF-beta and EGF). In contrast, fibroblasts did not proliferate in basal medium supplemented with platelet-poor plasma and the addition of PDGF alone stimulated fibroblast proliferation to the same extent as 10% fetal bovine serum. Supplementation with other growth factors did not further enhance the response of fibroblasts to PDGF. These results emphasize the differences in proliferative responses between human bone-derived cells and human fibroblasts, and indicate that the factors responsible for osseous regeneration in vivo may differ from those factors which regulate repair of soft tissue wounds.
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PMID:Study of the growth factor requirements of human bone-derived cells: a comparison with human fibroblasts. 278 49

In cultured normal rat liver epithelial cells, the specific activity and/or isozyme expression of NADH-diaphorase (NADH-D), pyruvate kinase (PK), glucose-6 phosphate dehydrogenase (G6PD), gamma-glutamyl transpeptidase (GGT), and alkaline phosphatase (AP) were markedly dependent on the growth state of the cultures. Proliferating, preconfluent cells had higher specific activities of PK, NADH-D, and G6PD but lower activities of GGT and AP than did the more stationary confluent cells. Addition of epidermal growth factor [EGF] to the media of proliferating cells enhanced the specific activities of PK, NADH-D, G6PD, GGT, and lactate dehydrogenase (LDH) of these cells, but the specific activity of AP was markedly depressed. The increase in activity of PK and GGT by EGF appeared to involve new protein synthesis, whereas the effect of EGF on AP appeared to involve the EGF-directed suppression of the synthesis of a form of AP that is produced exclusively by cells in confluent cultures. Furthermore, the preconfluent cells were more responsive to the action of EGF on AP than were confluent cells, i.e., the EGF-mediated decrease in AP activity was seen at lower concentration in preconfluent than in confluent cells. Paradoxically, confluent cells exhibited a two-to threefold higher capacity to bind [125 I]EGF because of an increase in surface receptor number. The results of this study indicate that enzymatic or other biochemical studies performed on cultured cells must take into account the growth-state of the cultures. EGF can modulate enzyme activity in growing and nongrowing cells; one effect of EGF is to maintain higher activity of glycolytic enzymes, suggesting that EGF or EGF-like factors may contribute to the high rate of glycolysis in certain neoplasms.
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PMID:The effects of epidermal growth factor and the state of confluence on enzymatic activities of cultured rat liver epithelial cells. 286 16

A synthetic gene for human epidermal growth factor (hEGF) was joined to a sequence encoding the signal peptide of Escherichia coli alkaline phosphatase. This hybrid gene was placed under the control of the alkaline phosphatase gene (phoA) promoter in a recombinant plasmid, which was used to transfect E. coli. The hybrid protein that was expressed in host cells under conditions of phosphate limitation was processed accurately during the secretion process, and mature hEGF was recovered in the periplasmic fraction. On the other hand, no EGF was detected in the periplasmic space when the synthetic hEGF gene was not accompanied by the phoA signal sequence.
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PMID:Synthesis and secretion of human epidermal growth factor by Escherichia coli. 390 48


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