Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The c-fos nuclear oncoprotein is rapidly induced when the growth of normal cells is initiated by mitogens, and it is also synthesized in several cell systems in response to stimuli that do not cause cell proliferation. When expressed inappropriately, c-fos, and its retroviral counterpart v-fos, can transform susceptible cells in vivo and in vitro. We have developed a simple and sensitive ELISA for the c-fos and v-fos proteins. Fos proteins are captured from cell lysates by an antibody specific for an amino-terminal peptide substantially conserved between v-fos and c-fos; the captured proteins are recognised by a second antibody against a different peptide sequence also conserved in the two proteins. The second antibody has been conjugated to alkaline phosphatase to provide an enzyme label; bound alkaline phosphatase is measured with a sensitive cycling enzyme system that generates a coloured end-product. We show that the fos ELISA is immunologically specific and use it to monitor increased c-fos expression in serum-stimulated HeLa cells and human fibroblasts, and in mitogen-stimulated murine thymocytes.
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PMID:A sensitive enzyme-linked immunosorbence assay for the c-fos and v-fos oncoproteins. 312 20

Human osteosarcoma and fibrosarcoma cell lines were investigated for alterations in oncogenes, tumor suppressor genes, and growth factors, all of which have been implicated in tumor formation. Characterization of oncogenes that are involved in osteosarcoma formation, including the c-fos and c-myc oncogenes, indicated that all six osteosarcoma cell lines examined had 5- to 20-fold amplification of the c-myc oncogene, whereas neither of two fibrosarcoma cell lines c-myc amplification. Interestingly, only three of six osteosarcoma cell lines displayed altered c-myc immediate-early gene function. c-fos was found to be normal, both at the gene and functional levels, in all six osteosarcoma and both fibrosarcoma cell lines tested. Characterization of two tumor suppressor genes, p53 and RB1, that have been implicated in osteosarcoma formation indicated that p53 was altered in five of six osteosarcoma cell lines, whereas RB1 was altered in only two or six of these cell lines. Neither RB1 nor p53 was found to be altered in the fibrosarcoma cell lines tested. An additional transformation marker, autocrine growth-factor production, was observed in all six osteosarcoma cell lines and both fibrosarcoma cell lines examined. Finally, the differentiation state of the osteosarcoma cell lines was investigated via the bone differentiation markers alkaline phosphates and osteocalcin. Alkaline phosphatase activity was observed in four of six osteosarcoma cell lines but not in the two fibrosarcoma cell lines examined. The alkaline phosphatase activity was a result of the expression of the bone/liver/kidney alkaline phosphatase isoform. High-level osteocalcin expression was observed in one of the osteosarcoma cell lines but not in the two fibrosarcoma cell lines examined, although all cell lines demonstrated low-level osteocalcin expression. Together, these data demonstrate that relatively undifferentiated osteosarcomas commonly display c-myc amplification, p53 and RB1 mutation, and autocrine growth-factor production, all of which may play a role in osteosarcomagenesis.
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PMID:Analysis of oncogenes, tumor suppressor genes, autocrine growth-factor production, and differentiation state of human osteosarcoma cell lines. 757 9

The clinical effects of thyroid hormones on bone in hypo- and hyperthyroidism are well known but their fundamental role in the regulation of bone remodeling is still poorly understood. In this review the current literature is summarized and experimental data from our laboratory are presented. The direct stimulation of bone resorption by thyroid hormones in organ culture, which in part is mediated by prostaglandins and TGF-beta, and the effect of different agents thereon are reviewed. More recent data concerning thyroid hormone action in the osteoblastic cell line MC3T3E1, are summarized. From their effect on proliferation and alkaline phosphatase activity, we conclude that thyroid hormones accelerate osteoblastic differentiation. The regulation of the transcriptional expression of certain genes by nuclear T3 receptors and their effect on osteoblastic target genes like IGF-I are reviewed. In addition a novel role of triiodothyronine as inhibitor of growth factor induced transcriptional expression of regulatory genes (c-fos, c-jun) is suggested.
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PMID:The regulatory role of thyroid hormones in bone cell growth and differentiation. 760 82

Although mechanical forces regulate bone mass and morphology, little is known about the signals involved in that regulation. External force application increases periosteal bone formation by increasing surface activation and formation rate. In this study, the early tibial periosteal response to external loads was compared between loaded and nonloaded contralateral tibia by examining the results of blot hybridization analyses of total RNA. To study the impact of external load on gene expression, RNA blots were sequentially hybridized to cDNAs encoding the protooncogene c-fos, cytoskeletal protein beta-actin, bone matrix proteins alkaline phosphatase (ALP), osteopontin (Op), and osteocalcin (Oc), and growth factors insulin-like growth factor I (IGF-I) and transforming growth factor-beta (TGF-beta). The rapid yet transient increase in levels of c-fos mRNA seen within 2 hours after load application indirectly suggests that the initial periosteal response to mechanical loading is cell proliferation. This is also supported by the concomitant decline in levels of mRNAs encoding bone matrix proteins ALP, Op, and Oc, which are typically produced by mature osteoblasts. Another early periosteal response to mechanical load appeared to be the rapid induction of growth factor synthesis as TGF-beta and IGF-I mRNA levels were increased in the loaded limb with peak levels being observed 4 hours after loading. These data indicate that the acute periosteal response to external mechanical loading was a change in the pattern of gene expression which may signal cell proliferation. The altered pattern of gene expression observed in the present study supports previous evidence of increased periosteal cell proliferation seen both in vivo and in vitro following mechanical loading.
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PMID:Mechanical loading stimulates rapid changes in periosteal gene expression. 789 87

The present study was performed to clarify second messenger signaling in parathyroid hormone (PTH)-induced c-fos gene expression, to characterize the participation of the c-fos gene in the regulation of osteoblast proliferation and function as well as osteoclast-like cell formation by PTH and to compare these effects of PTH with those of PTH-related peptide (PTHrP). Both human (h) PTH-(1-34) and hPTHrP-(1-34) at 10(-8) M induced a transient c-fos gene expression to a similar degree in osteoblastic osteosarcoma cells, UMR-106. N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP) as well as Sp-diastereoisomer of adenosine cyclic 3',5'-phosphorothioate (Sp-cAMPS), an activator of cAMP-dependent protein kinase (PKA), induced a weak c-fos gene expression. Although Rp-diastereoisomer of adenosine cyclic 3',5'-phosphorothioate (Rp-cAMPS), an inhibitor of PKA, almost completely antagonized dbCAMP- and Sp-cAMPS-induced expression of c-fos gene, it did not cause an obvious inhibition of PTH- or PTHrP-induced expression. Phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), induced an intense expression of the c-fos gene, while 4 alpha-phorbol 12,13-didecanoate (4 alpha PDD), incapable of activating PKC, and calcium ionophores (A23187 and ionomycin) did not. Protein kinase C inhibitor (H-7, 50 microM) completely blocked the expression of the c-fos gene by PTH as well as by PTHrP). Antisense oligodeoxynucleotides (as-ODN) complementary to c-fos mRNA, which have been shown to inhibit its mRNA translation, at 1 microM significantly antagonized PTH- and PTHrP-induced inhibition of [3H] thymidine incorporation and stimulation of osteoclast-like cell formation in the presence of osteoblasts, but not an increase in alkaline phosphatase activity, compared to control oligodeoxynucleotides with same nucleotides as as-ODN but with a random sequence. The present study indicates the involvement of PKC system in c-fos gene expression by PTH as well as PTHrP and also indicates the involvement of the c-fos gene in the regulation of bone cell physiology by PTH and PTHrP.
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PMID:Second messenger signaling of c-fos gene induction by parathyroid hormone (PTH) and PTH-related peptide in osteoblastic osteosarcoma cells: its role in osteoblast proliferation and osteoclast-like cell formation. 796 20

This study examines the mechanism by which TGF-beta 1, an important mediator of cell growth and differentiation, blocks the differentiation of normal rat diploid fetal osteoblasts in vitro. We have established that the inability for pre-osteoblasts to differentiate is associated with changes in the expression of cell growth, matrix forming, and bone related genes. These include histone, jun B, c-fos, collagen, fibronectin, osteocalcin, alkaline phosphatase, and osteopontin. Morphologically, the TGF-beta 1-treated osteoblasts exhibit an elongated, spread shape as opposed to the characteristic cuboidal appearance during the early stages of growth. This is followed by a decrease in the number of bone nodules formed and the amount of calcium deposition. These effects on differentiation can occur without dramatic changes in cell growth if TGF-beta 1 is given for a short time early in the proliferative phase. However, continuous exposure to TGF-beta 1 leads to a bifunctional growth response from a negative effect during the proliferative phase to a positive growth effect during the later matrix maturation and mineralization phases of the osteoblast developmental sequence. Extracellular matrix genes, fibronectin, osteopontin and alpha 1(I) collagen, are altered in their expression pattern which may provide an aberrant matrix environment for mineralization and osteoblast maturation and potentiate the TGF-beta 1 response throughout the course of osteoblast differentiation. The initiation of a TGF-beta 1 effect on cell growth and differentiation is restricted to the proliferative phase of the culture before the cells express the mature osteoblastic phenotype. Second passage cells that are accelerated to differentiate by the addition of dexamethasone or by seeding cultures at a high density are refractory to TGF-beta 1. These in vitro results indicate that TGF-beta 1 exerts irreversible effects at a specific stage of osteoblast phenotype development resulting in a potent inhibition of osteoblast differentiation at concentrations from 0.1 ng/ml.
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PMID:TGF beta alters growth and differentiation related gene expression in proliferating osteoblasts in vitro, preventing development of the mature bone phenotype. 804 Jan 90

Lysophosphatidic acid (LPA) is an important constituent of serum and shares its mitogenic activity. Serum induction of several genes is regulated, at least in part, by sequences related to the c-fos serum response element (SRE). A Rat-2 fibroblast cell line containing the beta-galactosidase reporter gene under SRE control was treated with LPA. Lysophosphatidic acid induced a time- and dose-dependent increase in beta-galactosidase activity. After 5 hours of treatment with 1-oleoyl-LPA a 3-fold increase in beta-galactosidase activity was observed. In contrast, endogenous alkaline phosphatase activity did not change in parallel with the beta-galactosidase activity indicating that the induction was specific. Various LPAs with different acyl groups in the sn-1 position induced beta-galactosidase activity with a rank order potency of 1-oleoyl-LPA > 1-palmitoyl-LPA > or = 1-myristoyl-LPA > 1-stearoyl-LPA. Phosphatidic acid was approximately equal to 1-stearoyl-LPA. Neither the calcium ionophore (A23187) nor 12-O-tetradecanoylphorbol 13-acetate, induced beta-galactosidase activity. These data suggest that LPA may exert some of its effects by regulation of SRE controlled genes.
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PMID:Activation of serum response element-regulated genes by lysophosphatidic acid. 812 83

The present study was performed to examine whether calcitonin directly acted on mouse osteoblastic MC3T3-E1 cells to stimulate the mRNA expression of insulin-like growth factor-1 (IGF-1) and c-fos, followed by an increase in their proliferation and differentiation. Eel calcitonin increased [3H]thymidine incorporation and alkaline phosphatase activity as well as the mRNA expression of type 1 collagen and osteocalcin which were characteristic of osteoblasts. Eel calcitonin (10(-8)M) induced c-fos mRNA transiently after its addition, followed by gene expression of IGF-1, an important autocrine/paracrine growth factor in the regulation of osteoblastic proliferation. We first demonstrated that calcitonin directly acted on osteoblasts to stimulate transcription of c-fos and IGF-1 genes as well as functional phenotypes including type 1 collagen and osteocalcin.
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PMID:Calcitonin directly acts on mouse osteoblastic MC3T3-E1 cells to stimulate mRNA expression of c-fos, insulin-like growth factor-1 and osteoblastic phenotypes (type 1 collagen and osteocalcin). 813 34

We have generated transgenic mice expressing the proto-oncogene c-fos from an H-2Kb class I MHC promoter as a tool to identify and isolate cell populations which are sensitive to altered levels of Fos protein. All homozygous H2-c-fosLTR mice develop osteosarcomas with a short latency period. This phenotype is specific for c-fos as transgenic mice expressing the fos- and jun-related genes, fosB and c-jun, from the same regulatory elements do not develop any pathology despite high expression in bone tissues. The c-fos transgene is not expressed during embryogenesis but is expressed after birth in bone tissues before the onset of tumor formation, specifically in putative preosteoblasts, bone-forming osteoblasts, osteocytes, as well as in osteoblastic cells present within the tumors. Primary and clonal cell lines established from c-fos-induced tumors expressed high levels of exogenous c-fos as well as the bone cell marker genes, type I collagen, alkaline phosphatase, and osteopontin/2ar. In contrast, osteocalcin/BGP expression was either low or absent. All cell lines were tumorigenic in vivo, some of which gave rise to osteosarcomas, expressing exogenous c-fos mRNA, and Fos protein in osteoblastic cells. Detailed analysis of one osteogenic cell line, P1, and several P1-derived clonal cell lines indicated that bone-forming osteoblastic cells were transformed by Fos. The regulation of osteocalcin/BGP and alkaline phosphatase gene expression by 1,25-dihydroxyvitamin D3 was abrogated in P1-derived clonal cells, whereas glucocorticoid responsiveness was unaltered. These results suggest that high levels of Fos perturb the normal growth control of osteoblastic cells and exert specific effects on the expression of the osteoblast phenotype.
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PMID:Osteoblasts are target cells for transformation in c-fos transgenic mice. 833 93

Increased levels of c-fos and c-jun expression have been observed in differentiating epithelial cells. However, no data are available on activator protein 1 (AP-1) activity during keratinocyte differentiation. In this work we investigated c-fos and c-jun gene expression and AP-1-(12-O-tetradecanoylphorbol-13-acetate)-responsive enhancer element (TRE) binding activity during keratinocyte differentiation utilizing both authentic and in culture-reconstituted human epidermis. We demonstrate that: (i) in reconstituted epidermis, non-differentiated and differentiated keratinocytes express equivalent levels of c-Jun, while in reconstituted epidermis permanently grafted onto athymic mice, as well as in authentic epidermis, c-Jun is predominantly expressed in the granular layer of the tissue. Equivalent levels of c-fos expression have been found in all the layers of both reconstituted and authentic epidermis. (ii) Nuclear extracts from cultures enriched in differentiated keratinocytes display an 80-90% reduction of AP-1 activity when compared to extracts from cultures enriched in nondifferentiated cells. (iii) Cytosolic extracts obtained from cultures enriched in differentiated cells reduce, in a concentration-dependent manner, the AP-1 activity present in nuclear extracts of both mammalian and Drosophila cells. (iv) The specific TRE binding activity of a recombinant c-Jun protein is significantly reduced by cytosolic extracts of differentiated keratinocytes, while the specific DNA binding of the purified recombinant human homeoprotein HOX4B is not. (v) The dephosphorylation, by alkaline phosphatase, of cytosolic extracts increases the inhibitory activity already present or makes evident a latent activity.
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PMID:AP-1 activity during normal human keratinocyte differentiation: evidence for a cytosolic modulator of AP-1/DNA binding. 841 91


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