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)

Guided tissue regeneration (GTR) is a concept that evolved from the development of membrane barrier techniques which allow the repopulation of periodontal wounds by desirable cells, resulting in a so-called new attachment apparatus. To understand the biological mechanisms involved in membrane barrier-led periodontal healing, the histological localization of macromolecules phenotypical of bone and cementum formation was investigated in regenerating human periodontal tissues harvested after healing by placing barriers on teeth untreatable except by extraction. Using immunolocalization techniques, frozen sections of soft tissues and hard tissues under GTR barriers were stained with antibodies to osteonectin (LB-BON-II) and bone sialoprotein (BSP) (LF-6); alkaline phosphatase (AP) was detected histochemically. Frozen sections of regenerating periodontal tissue demonstrated the presence of spindle-shaped, fibroblast-like cells entrapped in a dense fibrillar extracellular matrix. Rounded cells aggregated to form nodules heavily stained by the Alcian blue method, indicating the presence of proteoglycans and strongly resembling those noted in hard-tissue sections. At the electron-microscopic level, the cytoplasm of the elongated cells had numerous cisternae of endoplasmic reticulum and Golgi saccules, indicating metabolic activity. Striated collagen fibres were scattered throughout the field of the sections. AP-stained soft-tissue sections demonstrated the presence cell-bound and extracellular AP. Osteonectin antibody staining confirmed the presence of this macromolecule in the extracellular matrix, particularly in the area of the cellular nodules. The dense network of connective tissue fibres was also stained.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Immunolocalization of bone matrix macromolecules in human tissues regenerated from periodontal defects treated with expanded polytetrafluoroethylene membranes. 757 38

Effects of dexamethasone and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] were studied in cultures of adult human marrow stromal cells. In primary culture, dexamethasone (10(-8) M) increased the number of fibroblast colonies formed but decreased their average size. The number of colonies expressing alkaline phosphatase activity was increased, consistent with the enhancement of osteogenic differentiation by this glucocorticoid. In secondary culture, osteogenic differentiation was assessed by measurement of the steady-state levels of particular mRNAs that are characteristic of cells of the osteoblast lineage. The mRNAs for alpha 1(I)-procollagen, alkaline phosphatase, osteopontin and bone sialoprotein were expressed under all culture conditions used. In contrast, osteocalcin mRNA expression was detectable only in cultures treated with 1,25(OH)2D3 (10(-8) M). Addition of 1,25(OH)2D3 to control increased the expression of the mRNAs for alkaline phosphatase and osteopontin but had no significant effect on bone sialoprotein expression. The highest levels of expression of the mRNAs for alkaline phosphatase, bone sialoprotein and osteocalcin were observed in dexamethasone-treated cultures to which 1,25(OH)2D3 had been added. These results demonstrate that, as earlier found in other species, dexamethasone and 1,25(OH)2D3 promote the osteogenic differentiation of human marrow stromal cells as measured by expression of these osteogenic markers.
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PMID:The effects of dexamethasone and 1,25-dihydroxyvitamin D3 on osteogenic differentiation of human marrow stromal cells in vitro. 769 7

This study evaluated a rapid biomineralization phenomenon exhibited by an osteoblastic cell line, UMR 106-01 BSP, when treated with either organic phosphates [beta-glycerophosphate (beta-GP), Ser-P, or Thr-P], inorganic phosphate (P(i)), or calcium. In a dose-dependent manner, these agents (2-10 mM) stimulated confluent cultures to deposit mineral in the cell layer (ED50 of approximately 4.6 mM for beta-GP (30 +/- 2 nmol Ca2+/microgram DNA) and approximately 3.8 mM (29 +/- 2 nmol Ca2+/microgram DNA) for P(i)) with a plateau in mineral formation by 20 h (ET50 approximately 12-15 h). beta-GP or P(i) treatment yielded mineral crystals having an x-ray diffraction pattern similar to normal human bone. Alizarin red-S histology demonstrated calcium mineral deposition in the extracellular matrix and what appeared to be intracellular paranuclear staining. Electron microscopy revealed small, needle-like crystals associated with fibrillar, extracellular matrix deposits and intracellular spherical structures. Mineral formation was inhibited by levamisole (ED50 approximately 250 microM), pyrophosphate (ED50 approximately 1-10 microM), actinomycin C1 (500 ng/ml), cycloheximide (50 micrograms/ml), or brefeldin A (1 microgram/ml). These results indicate that UMR 106-01 BSP cells form a bio-apatitic mineralized matrix upon addition of supplemental phosphate. This process involves alkaline phosphatase activity, ongoing RNA and protein synthesis, as well as Golgi-mediated processing and secretion.
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PMID:Rapidly forming apatitic mineral in an osteoblastic cell line (UMR 106-01 BSP). 772 67

We report the establishment of a human fetal osteoblast cell line derived from biopsies obtained from a spontaneous miscarriage. Primary cultures isolated from fetal tissue were transfected with a gene coding for a temperature-sensitive mutant (tsA58) of SV40 large T antigen along with a gene coding for neomycin (G418) resistance. Individual neomycin resistant colonies were screened for alkaline phosphatase (AP)-specific staining. The clone with the highest AP level, hFOB 1.19, was examined further for other osteoblast phenotypic markers. Incubation of hFOB cells at the permissive temperature (33.5 degrees C) resulted in rapid cell division, whereas little or no cell division occurred at the restrictive temperature (39.5 degrees C). Both AP activity and osteocalcin (OC) secretion increased in a dose-dependent manner following dihydroxyvitamin D3 (1,25-D3) treatment when cultured at either temperature. However, AP and 1,25-D3-induced OC levels were elevated in confluent hFOB cells cultured at 39.5 degrees C compared with 33.5 degrees C. Treatment of hFOB cells with 1-34 parathyroid hormone (PTH) resulted in an increase in cAMP levels. Upon reaching confluence, hFOB cultures went through programmed differentiation and formed mineralized nodules as observed by von Kossa staining. Further, immunostaining of postconfluent, differentiated hFOB cells showed that high levels of osteopontin, osteonectin, bone sialoprotein, and type I collagen were expressed. Therefore, the clonal cell line hFOB 1.19 provides a homogeneous, rapidly proliferating model system to study certain stages of human osteoblast differentiation.
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PMID:Development and characterization of a conditionally immortalized human fetal osteoblastic cell line. 775 97

Osteocyte-like cells were prepared by sequentially treating calvaria from newborn rats with collagenase and chelating agents. On a reconstituted gel of basement membrane components, cells from the third collagenase digest displayed a round shape and expressed the highest level of alkaline phosphatase with minimal osteocalcin deposition into the matrix. On the other hand, cells derived from the interior after EDTA treatment exhibited well-developed dendritic cell processes and expressed essentially no alkaline phosphatase. The latter population also showed quite distinct characteristics such as higher extracellular activities of casein kinase II and ecto-5'-nucleotidase and the extracellular accumulation of a large amount of osteocalcin associated with mineral. These diverse phenotypic and protein expressions as well as the sites from which each population of cells were recovered strongly suggest that we have isolated osteoblastic and osteocytic cells. Bone sialoprotein II was extracellularly phosphorylated by casein kinase II in osteocytic cells but not in osteoblastic cells. We discuss the possibility that differentiation of young osteocytes from osteoblasts may facilitate the biochemical sequence of mineral deposition in the bone matrix.
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PMID:Matrix mineralization and the differentiation of osteocyte-like cells in culture. 775 2

The neonatal rat mandible was used as a model to study bone formation, mineralization, quiescence, and resorption, using immunolocalization and a variety of tissue-processing techniques. Monospecific antibodies for osteopontin (OPN), bone sialoprotein (BSP), alkaline phosphatase (AP) and alpha 2HS-glycoprotein (alpha 2HS-GP) were used on fixed paraffin-embedded tissue, fixed frozen tissue and unfixed frozen tissue. Immunostaining was correlated with mineral content by two procedures, the von Kossa and the morin techniques. Morin fluorescence was used with secondary immunostaining to provide a way of closely correlating bone matrix proteins and matrix mineralization. Co-immunolocalization procedures were used to compare the sites of bone proteins in the matrix. AP was found earliest during osteogenic cell differentiation, appearing in the preosteoblasts, followed by OPN and BSP, which first appeared in osteoblasts. alpha 2HS-GP expression was not observed in cells. The results provide clear evidence for the presence of OPN in osteoid, while BSP and alpha 2HS-GP were confined to the mineralized matrix. Immunostaining of bone proteins is highly technique-dependent: immunolocalization investigations required several methods of approach to ensure adequate demonstration of these proteins in cells and matrix. The results support the contention that osteopontin is multifunctional in bone metabolism, and that alpha 2HS-GP, though produced in the liver, is abundant in bone matrix and may also have a function in bone metabolism.
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PMID:Bone matrix proteins in osteogenesis and remodelling in the neonatal rat mandible as studied by immunolocalization of osteopontin, bone sialoprotein, alpha 2HS-glycoprotein and alkaline phosphatase. 779 28

Treatment of the U-2 OS human osteosarcoma cell line with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) dramatically decreased the rate of DNA synthesis. This decrease in proliferation as well as the change in morphology of the TPA-treated cells can be blocked by the protein kinase C inhibitor GF 109203X. The U-2 OS cells are known to express the c-sis oncogene [platelet-derived growth factor (PDGF) B-chain], PDGF-A, and receptors for PDGF, thus providing a potential autocrine loop of growth stimulation. TPA was found to induce the expression of both the PDGF-A and the PDGF-B chains. However, the levels of the PDGF receptor beta subunits and of the PDGF-BB inducable tyrosine phosphorylation of the PDGF receptor were markedly reduced. The TPA treatment of the U-2 OS cells also induced changes typical for maturing bone cells, such as increased expression levels of alkaline phosphatase and osteopontin. The expression levels of type I collagen and bone sialoprotein were reduced. The results show a TPA-dependent down-regulation of the PDGF receptor beta subunits that correlates with an increased expression of osteoblast phenotypic markers.
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PMID:Phenotypic modification of human osteosarcoma cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. 779 13

Tetranectin is a protein shared by the blood and the extracellular matrix. Tetranectin is composed of four identical, noncovalently bound polypeptides each with a molecular mass of approximately 21 kD. There is some evidence that tetranectin may be involved in fibrinolysis and proteolysis during tissue remodeling, but its precise biological function is not known. Tetranectin is enriched in the cartilage of the shark, but the gene expression pattern in the mammalian skeletal system has not been determined. In the present study we have examined the expression pattern and putative function of tetranectin during osteogenesis. In the newborn mouse, strong tetranectin immunoreactivity was found in the newly formed woven bone around the cartilage anlage in the future bone marrow and along the periosteum forming the cortex. No tetranectin immunoreactivity was found in the proliferating and hypertrophic cartilage or in the surrounding skeletal muscle. Using an in vitro mineralizing system, we examined osteoblastic cells at different times during their growth and differentiation. Tetranectin mRNA appeared in the cultured osteoblastic cells in parallel with mineralization, in a pattern similar to that of bone sialoprotein, which is regarded as one of the late bone differentiation markers. To explore the putative biological role of tetranectin in osteogenesis we established stably transfected cell lines (PC12-tet) overexpressing recombinant tetranectin as evidenced by Northern and Western blot analysis and immunoprecipitation. Both control PC12 cells and PC12-tet cells injected into nude mice produced tumors containing bone material, as evidenced by von Kossa staining for calcium and immunostaining with bone sialoprotein and alkaline phosphatase antiserum. Nude mice tumors established from PC12-tet cells contained approximately fivefold more bone material than those produced by the untransfected PC12 cell line or by the PC12 cells transfected with the expression vector with no insert (Mann Whitney rank sum test, p < 0.01), supporting the notion that tetranectin may play an important direct and/or indirect role during osteogenesis. In conclusion, we have established a potential role for tetranectin as a bone matrix protein expressed in time and space coincident with mineralization in vivo and in vitro.
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PMID:A potential role for tetranectin in mineralization during osteogenesis. 779 25

Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10(-5) M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.
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PMID:Stimulation of human osteoblast differentiation and function by ipriflavone and its metabolites. 786 17

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine with both anabolic and catabolic effects on bone tissue. To investigate the effect of LIF on bone formation in the absence of a resorption cycle, we used fetal rat calvaria cell cultures and quantified bone nodule production, which provides a colony assay to analyze the effects of factors on osteoprogenitor differentiation and bone formation. In these cultures, dexamethasone (Dex) stimulates bone nodule formation. In dose-response experiments, LIF inhibited bone nodule formation by cells cultured with (+Dex; ID50 = 250 U/ml) or without (-Dex; ID50 = 30 U/ml) 10(-8) M Dex. Residual nodules were small and poorly mineralized. Continuous exposure to LIF (500 U/ml) up to day 25 did not affect either the growth rate or saturation density of the cultures, but decreased alkaline phosphatase activity and bone nodule production, with greater inhibition in -Dex cultures. Exposure to LIF (500 U/ml) for 3 days early during nodule formation (about day 10) reduced bone nodule numbers to the same extent as continuous treatment in -Dex cultures and significantly, but less markedly, in +Dex cultures; earlier and later pulses had no effect. Northern blot analysis of expression of messenger RNAs of bone related proteins in cultures pulsed (-Dex) at various stages of development showed marked inhibition of alkaline phosphatase, bone sialoprotein, and osteocalcin; slight inhibition of type I collagen; early stimulation of osteopontin; and no effect on Secreted Protein, Acidic and Rich in Cysteine/osteonectin. These results suggest that LIF is an inhibitor of bone nodule formation in these cultures, acting at a stage when late osteoprogenitors and/or early osteoblasts are present, and that Dex may modulate the effects of LIF by shifting effective doses to higher concentrations.
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PMID:Leukemia inhibitory factor inhibits osteogenic differentiation in rat calvaria cell cultures. 789 51


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