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)

A human dental pulp tissue was explanted in culture and the outgrowing cells were transfected with the plasmid, pMT1-neo, which included the early region of SV 40 DNA and the neomycin-resistant gene. The transfected cells were cloned and cultured beyond the period of senescence for the non-transfected HOP cells, over 170 passages (360 population doubling levels and 730 days). The characteristics of the transfected LSC cells and the non-transfected HOP cells were investigated during in vitro aging. The results were as follows: 1. The alkaline phosphatase (ALPase) activity of the HOP cells decreased as the culture passages increased. In contrast, the ALPase activity of the LSC cells did not change during the entire serial culture period. 2. The ALPase inhibitory test indicated that the ALPase in the LSC cells was the bone/liver/kidney type. 3. The addition of 250 micrograms/ml of L-ascorbic acid resulted in an increased collagen synthesis compared with that of 50 micrograms/ml. 4. The growth rate and the ALPase activity of the LSC cells were affected by 1 alpha, 25-dihydroxyvitamin D3, L-ascorbic acid, beta-sodium glycerophosphate, epidermal growth factor or transforming growth factor-beta even after the serial culture. These results suggest that the LSC cells preserve some properties of the dental pulp and may be useful in the future research for exploring the mechanisms of the dental hard tissue formation and for testing the biocompatibility of the dental restorative materials.
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PMID:[Immortalization of human dental pulp cells with transfecting of the plasmid, pMT1-neo]. 255 37

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 present study examines how the mitogenic and differentiation functions of transforming growth factor-beta (TGF-beta) are modulated by basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in primary cultures of rat osteoblast-like (ROB) cells. TGF-beta, bFGF, and EGF individually stimulated [3H]thymidine incorporation and cell proliferation in a dose range of 0.01-10 ng/ml. When studied in combination, high doses of bFGF and EGF were additive to low doses of TGF-beta. The additive effects of bFGF and EGF on mitogenesis diminished with increasing doses of TGF-beta. These three factors also decreased alkaline phosphatase activity individually within the same dose range. When cells were treated with the combined factors, only high doses of bFGF and EGF were additive to the TGF-beta inhibition. We were unable to detect any change in collagen synthesis with each individual factor or in combined treatments. In addition, TGF-beta or bFGF alone or in combination did not affect fibronectin synthesis. Our studies showed that the biological functions of TGF-beta can be modulated by bFGF and EGF in ROB cells. The pattern of modulation is varied depending on the specific function examined.
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PMID:Modulation of transforming growth factor-beta actions in rat osteoblast-like cells: the effects of bFGF and EGF. 263 28

Numerous reports have appeared in the literature indicating phenotypic heterogeneity among cells of the osteoblastic lineage. This diversity may be due to either certain stages of differentiation or a subspecialization of already terminally differentiated osteoblasts. To obtain answers to this question, we report on studies undertaken to clone bone cell populations from 1 day postnatal rat calvaria which express well defined differences in phenotype. To achieve this goal, we have used the soft agarose cloning technique which previously has almost exclusively been applied to clone cells of neoplastic origin. The reason for being able to employ this method is based on the fact that bone cells can be induced by transforming growth factor-beta to reversibly acquire the transformed phenotype, an event expressed by anchorage-dependent bone cells to form progressively growing colonies in soft agarose. Individual colonies, harvested from agarose, were expanded to clonal bone cell populations. Characterizing 48 cell clones by detection of osteoblastic cell markers such as alkaline phosphatase activity, PTH- and prostaglandin-E2-induced adenylate cyclase activity, osteocalcin mRNA synthesis, as well as collagen synthesis, 7 subsets of osteoblastic cell types were identified. Each subset was found to express a distinct phenotype, indicated by the absence or presence of osteoblastic cell markers. Some clones, previously found not to exhibit any osteoblastic traits, developed PTH responsiveness when treated with insulin-like growth factor-I/transforming growth factor-beta, suggesting that these clones may originate from the osteoprogenitor cell pool. While most clonal cell populations were characterized as fully functional osteoblastic cells, some clones expressed merely 1, 2, or 3 osteoblastic markers, which suggests that they may represent stages of differentiation along the osteogenic pathway. In addition, other subclones displayed the capacity to synthesize osteocalcin and showed PTH and prostaglandin-E2 responsiveness, but were found to be devoid of alkaline phosphatase activity. Others expressed all osteoblastic cell markers except PTH responsiveness. The phenotypic constellation of the latter suggests that these cell clones may represent mature osteoblast-like cells, which, perhaps due to environmental circumstances present at the time of isolation, have become altered in accordance with the physiological requirements of the tissue.
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PMID:Evidence for heterogeneity of the osteoblastic phenotype determined with clonal rat bone cells established from transforming growth factor-beta-induced cell colonies grown anchorage independently in semisolid medium. 267 79

To determine the effects of transforming growth factor-beta (TGF-beta) on the different cell types that exist in bone, cell populations (I-IV), progressively enriched in osteoblastic cells relative to fibroblastic cells, were prepared from fetal rat calvaria using timed collagenase digestions. TGF-beta did not induce anchorage-independent growth of these cells, nor was anchorage-dependent growth stimulated in most populations studied, despite a two- to threefold increase in the synthesis of cellular proteins. In all populations the synthesis of secreted proteins increased 2-3.5-fold. In particular, collagen, fibronectin, and plasminogen activator inhibitor synthesis was stimulated. However, different degrees of stimulation of individual proteins were observed both within and between cell populations. A marked preferential stimulation of plasminogen activator inhibitor was observed in each population, together with a slight preferential stimulation of collagen; the effect on collagen expression being directed primarily at type I collagen. In contrast, the synthesis of SPARC (secreted protein acidic rich in cysteine/osteonectin was stimulated approximately two-fold by TGF-beta, but only in fibroblastic populations. Collectively, these results demonstrate that TGF-beta stimulates matrix production by bone cells and, through differential effects on individual matrix components, may also influence the nature of the matrix formed by different bone cell populations. In the presence of TGF-beta, osteoblastic cells lost their polygonal morphology and alkaline phosphatase activity was decreased, reflecting a suppression of osteoblastic features. The differential effects of TGF-beta on bone cell populations are likely to be important in bone remodeling and fracture repair.
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PMID:Differential effects of transforming growth factor-beta on the synthesis of extracellular matrix proteins by normal fetal rat calvarial bone cell populations. 316 38

The bone morphogenetic proteins were originally identified based on their ability to induce ectopic bone formation in vivo and have since been identified as members of the transforming growth factor-beta gene superfamily. It has been well established that the bone morphogenetic cytokines enhance osteogenic activity in bone marrow stromal cells in vitro. Recent reports have described how bone morphogenetic proteins inhibited myogenic differentiation of bone marrow stromal cells in vitro. In vivo, bone marrow stromal cells differentiate along the related adipogenic pathway with advancing age. The current work reports the inhibitory effects of the bone morphorphogenetic proteins on adipogenesis in a multipotent murine bone marrow stromal cell line, BMS2. When exposed to bone morphogenetic protein-2, the pre-adipocyte BMS2 cells exhibited the expected induction of the osteogenic-related enzyme, alkaline phosphatase. Following induction of the BMS2 cells with adipogenic agonists, adipocyte differentiation was assessed by morphologic, enzymatic, and mRNA markers. Flow cytometric analysis combined with staining by the lipophilic fluorescent dye, Nile red, was used to quantitate the extent of lipid accumulation within the BMS2 cells. By this morphologic criteria, the bone morphogenetic proteins inhibited adipogenesis at concentrations of 50 to 500 ng/ml. This correlated with decreased levels of adipocyte specific enzymes and mRNAs. The BMS2 pre-adipocytes constitutively expressed mRNA encoding bone morphogenetic protein-4 and this was inhibited by adipogenic agonists. Together, these findings demonstrate that bone morphogenetic proteins act as adipogenic antagonists. This supports the hypothesis that adipogenesis and osteogenesis in the bone marrow microenvironment are reciprocally regulated.
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PMID:Bone morphogenetic proteins inhibit adipocyte differentiation by bone marrow stromal cells. 759 60

This report describes skeletal site-related differences in human osteoblastic cell metabolism in studies of four patients. Northern analyses of the constitutive growth factor messenger ribonucleic acid (mRNA) expression pattern in mandibular and iliac crest-derived human osteoblastic cells (based on within-patient comparisons) revealed higher mRNA levels for strong mitogenic growth factors such as basic fibroblast growth factor (bFGF) and insulin-like growth factor II (IGF-II) in the rapidly proliferating and less alkaline phosphatase (ALP)-expressing mandibular osteoblastic cells compared to those in the lower bFGF and IGF-II mRNA levels in slowly proliferating iliac human osteoblastic cells exhibiting a higher ALP expression level. In contrast, transforming growth factor-beta (TGF beta) mRNA was more abundant in iliac human osteoblastic cells than in mandibular osteoblastic cells. Furthermore, we found that there was a proportionality, based on data from both sites, between the level of constitutive TGF beta mRNA and the response to exogenously administered bFGF or IGF-II. A comparable pattern of growth characteristics and mRNA expression was also observed in transformed human osteoblastic cells that had been subcloned in sublines expressing high and low levels of the human osteoblastic differentiation marker ALP. These findings are consistent with 1) skeletal site-related differences in human bone cell phenotypes, and 2) decreased IGF-II and bFGF expression and increased TGF beta expression and responsiveness to bFGF and IGF-II in human bone cells exhibiting a high ALP expression.
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PMID:Human bone cell phenotypes differ depending on their skeletal site of origin. 762 52

We studied the effects of transforming growth factor-beta and basic fibroblast growth factor on the regulation of proliferation and osteochondrogenic differentiation of periosteum-derived cells, which have the potential to differentiate into bone and hypertrophic cartilage in vitro. Histological observation revealed that transforming growth factor-beta stimulated chondrogenesis of periosteum-derived cells while basic fibroblast growth factor stimulated proliferation of fibroblast-like cells and inhibited osteochondrogenic differentiation. Immunohistochemical studies revealed that basic fibroblast growth factor inhibited the expression of osteocalcin. Transforming growth factor-beta enhanced uronic acid content but decreased DNA content, alkaline phosphatase activity, and calcium content. In contrast, basic fibroblast growth factor enhanced DNA content but decreased alkaline phosphatase activity, calcium content, and uronic acid content. In addition, transforming growth factor-beta shortened the time-course of gene expression of type-X collagen whereas basic fibroblast growth factor inhibited the gene expression. These results indicate that transforming growth factor-beta stimulates osteochondrogenic differentiation of periosteum-derived cells but inhibits proliferation. They also indicate that basic fibroblast growth factor stimulates proliferation of periosteum-derived cells but inhibits osteochondrogenic differentiation.
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PMID:Regulation of proliferation and osteochondrogenic differentiation of periosteum-derived cells by transforming growth factor-beta and basic fibroblast growth factor. 771 71

The latent form of transforming growth factor-beta (TGF-beta) is a component of the extracellular matrix of bone. The active form, when locally injected in vivo, stimulates both inflammation and ectopic bone formation. The present study was undertaken to determine if TGF-beta also stimulated mineralization by isolated rat calvarial osteoblasts cultured in collagen gels. Gels were used because they should mimic in vivo conditions better than classical monolayer culture. Compared to cells in monolayers, osteoblasts cultured in collagen gels exhibited slower growth, but higher alkaline phosphatase activity and mineral deposition. Cultured cells also synthesized the osteoblast-specific marker, osteocalcin. The increase in osteocalcin in cell layers was parallel to the increase in mineral deposition. In the presence of TGF-beta, neither cell growth nor alkaline phosphatase activity increased. Instead, a small decrease occurred in both parameters when compared to untreated cultures. Accumulation of collagen, the major component of the extracellular matrix where mineralization occurs, was similar in untreated and TGF-beta 1-treated cultures. However, 8 pM TGF-beta 1 dramatically suppressed mineral deposition in both types of cultures. Despite TGF-beta 1 stimulating a fourfold increase in lactic acid, the consequent increase in culture medium acidity did not account for the inhibitory effects of TGF-beta 1 on mineralization. These results demonstrate that collagen gel culture is an improved technique over conventional monolayer culture for demonstrating differentiated osteoblast function and sensitivity to TGF-beta 1. TGF-beta 1, at a concentration that has little effect on cell growth, alkaline phosphatase activity, or collagen accumulation, is a potent inhibitor of mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Transforming growth factor-beta inhibition of mineralization by neonatal rat osteoblasts in monolayer and collagen gel culture. 779 46

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


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