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)

Bone morphogenetic protein (BMP) is a family of cytokines that induce ectopic bone formation when implanted into muscular tissues. We reported that BMP-2 inhibits the terminal differentiation of C2C12 myoblasts and converts them into osteoblast lineage cells (Katagiri, T., Yamaguchi, A., Komaki, M., Abe, E., Takahashi, N., Ikeda, T., Rosen, V., Wozney, J. M., Fujisawa-Sehara, A., and Suda, T. (1994) J. Cell Biol. 127, 1755-1766). In the present study, we examined the molecular mechanism of the inhibitory effect of BMP-2 on terminal differentiation of myogenic cells. When either MyoD or myogenin cDNA was introduced into C3H10T1/2 (10T1/2) cells with a muscle-specific CAT reporter containing four copies of the right E-box of muscle creatine kinase (MCK) enhancer, the CAT activity was dose-dependently suppressed by BMP-2. Furthermore, BMP-2 inhibited the terminal differentiation of these subclonal 10T1/2 cells that stably expressed MyoD or myogenin into mature myotubes that expressed myosin heavy chain and troponin T. The differentiation of a subclone of the MyoD-transfected NIH3T3 cells into mature muscle cells was also inhibited by BMP-2. BMP-2 induced alkaline phosphatase activity in 10T1/2-derived, but not in NIH3T3-derived MyoD-transfected cells. These cells constitutively expressed exogenous MyoD and myogenin, which were localized exclusively in the nuclei irrespective of the presence and the absence of BMP-2. However, these cells failed to express the mRNAs of endogenous myogenic factors and MCK when cultured with BMP-2. In the electrophoresis mobility shift assay using nuclear extracts of the myogenic cells, MyoD and myogenin bound to the right E-box in the enhancer region of the MCK gene even in the presence of BMP-2. These results suggest that BMP-2 inhibits the terminal differentiation of myogenic cells by suppressing the transcriptional activity of the myogenic factors.
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PMID:Bone morphogenetic protein-2 inhibits terminal differentiation of myogenic cells by suppressing the transcriptional activity of MyoD and myogenin. 902 93

Normal bone formation is a prolonged process that is carefully regulated and involves sequential expression of growth regulatory factors by osteoblasts as they proliferate and ultimately differentiate. Since this orderly sequence of gene expression by osteoblasts suggests a cascade effect, and BMP-2 is capable of initiating and maintaining this effect, we examined the effects of BMP-2 on expression of other BMPs and compared these effects with the expression pattern of bone cell differentiation marker genes in primary cultures of fetal rat calvarial (FRC) osteoblasts. To examine the gene expression profile during bone cell differentiation and bone formation, we also examined the effects of rBMP-2 on bone formation in vivo and in vitro. rBMP-2 stimulated bone formation on the periosteal surface of mice when 500 ng/day rBMP-2 was injected subctaneously. When rBMP-2 was added to primary cultures of FRC osteoblasts, it accelerated mineralized nodule formation in a time and concentration-dependent manner (10-40 ng/ml). rBMP-2 (40 ng/ml) enhanced BMP-3 and -4 mRNA expression during the mineralization phase of primary cultures of FRC osteoblasts. Enhancement of BMP-3 and -4 mRNA expression by rBMP-2 was associated with increased expression of bone cell differentiation marker genes, alkaline phosphatase (ALP), type I collagen, osteocalcin (OC), osteopontin (OP), and bone sialoprotein (BSP). These results suggest that BMP-2 enhances expression of other BMP genes during bone cell differentiation. BMP-2 may act in a paracrine fashion in concert with other BMPs it induces to stimulate bone cell differentiation and bone formation during remodeling.
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PMID:Bone morphogenetic protein 2 (BMP-2) enhances BMP-3, BMP-4, and bone cell differentiation marker gene expression during the induction of mineralized bone matrix formation in cultures of fetal rat calvarial osteoblasts. 906 67

p53 protein regulates cell cycle progression and its absence will result in unlimited cell divisions required for immortalization of cells. Immortalized osteoblastic cell lines were established from p53 null mouse calvariae of normal phenotype. The clonal murine cell lines demonstrated osteoblastic phenotype as exemplified by alkaline phosphatase enzyme activity. They also express bone morphogenetic protein 2 (BMP2) mRNA. Addition of recombinant BMP2 to these cells dramatically increased the alkaline phosphatase activity in a dose dependent manner. In the absence of BMP2 these cells do not undergo osteoblastic differentiation. Treatment of these cells with recombinant bone morphogenetic protein 2 stimulated differentiated osteoblast formation, as determined by mineralized nodule formation. Thus, these immortalized cells in culture represent osteoblast progenitors that lack p53 protein and respond to osteogenic stimuli. These cell lines offer a model system to study the role of p53 in osteoblastic differentiation and programmed cell death. Also these cells will be useful in studying the effects of p53 on transcriptional regulation of osteoblast specific gene expression.
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PMID:Clonal osteoblastic cell lines from p53 null mouse calvariae are immortalized and dependent on bone morphogenetic protein 2 for mature osteoblastic phenotype. 907 Feb 48

To elucidate the biochemical mechanism of osteogenesis, the effect of matrix geometry upon the osteogenesis induced by bone morphogenetic protein (BMP) was studied. A series of five porous hydroxyapatites with different pore sizes, 106-212, 212-300, 300-400, 400-500, and 500-600 microns, was prepared. A block (approximately 5 x 5 x 1 mm, 40.0 mg) of each hydroxyapatite ceramics was combined with 4 micrograms of recombinant human BMP-2 and implanted subcutaneously into the back skin of rat. Osteoinductive ability of each implant was estimated by quantifying osteocalcin content and alkaline phosphatase activity in the implant up to 4 wk after implantation. In the ceramics of 106-212 microns, the highest alkaline phosphatase activity was found 2 wk after implantation, and the highest osteocalcin content 4 wk after implantation, consistent with the results observed with particulate porous hydroxyapatite [Kuboki, Y. et al. (1995) Connect. Tissue Res. 32: 219-226]. Comparison of the alkaline phosphatase activities at 2 wk and the osteocalcin contents at 4 wk after implantation revealed that the highest amount of bone was produced in the ceramics implants with pore size of 300-400 microns. In the ceramics with smaller or larger pore sizes, the amount of bone formation decreased as the pore size deviated from 300-400 microns. The results indicated that the optimal pore size for attachment, differentiation and growth of osteoblasts and vascularization is approximately 300-400 microns. This study using chemically identical but geometrically different cell substrata is the first demonstration that a matrix with a certain geometrical size is most favorable for cell differentiation.
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PMID:Pore size of porous hydroxyapatite as the cell-substratum controls BMP-induced osteogenesis. 908 6

Bone morphogenetic proteins (BMPs) are multifunctional proteins that comprise the largest subfamily of the transforming growth factor-beta. These proteins bind to types I and II serine/threonine kinase receptors. Ligand-induced heteromeric dimerization of these receptors is the key event in initiation of biological responses. We report here large-scale expression and purification of extracellular domain of the type I receptor for BMP-2/4, using a silkworm expression system. This soluble form of BMP receptor (sBMPR) was in monomer form in solution and bound to BMP-4 but not to activin or transforming growth factor-beta1. Surface plasmon resonance studies showed that kinetic parameters of sBMPR for BMP-4 consisted of a relatively rapid association rate constant (ka = 3.81 +/- 0.19 x 10(4) s-1 M-1) and an extremely slow dissociation rate constant (kd = 3.69 +/- 0.26 x 10(-4) s-1). From these two kinetic parameters, affinity was determined to be similar to that of the intact membrane-associated receptor expressed on COS cells. sBMPR inhibited the alkaline phosphatase activity in BMP responsive cell lines such as mouse osteoblastic cell MC3T3-E1 and bone marrow stromal cell ST2. These data indicate that the extracellular domain of type I receptor for BMP-2 and BMP-4 is sufficient for high-affinity binding to its ligands and should prove useful in understanding the role of BMP-2/4 in vivo, because a suitable high-affinity anti-BMP antibody has yet to be developed.
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PMID:Interaction between soluble type I receptor for bone morphogenetic protein and bone morphogenetic protein-4. 911 Oct 68

We have investigated single and combined effects of calciotropic hormones and growth factors on the regulation of alkaline phosphatase (ALP) activity and calcium metabolism in an optimized serum-free bone organ culture system of embryonic chick tibiae. Parathyroid hormone PTH(1-34) alone mobilized calcium from bone tissue time- and dose-dependently and inhibited ALP activity. Both the bisphosphonate (BM 21.0955) and to a lesser extent salmon calcitonin alone slightly increased calcium uptake and inhibited the stimulation of bone resorption by PTH(1-34). 1,25(OH)2D3 mobilized calcium and inhibited ALP activity in contrast to 24,25(OH)2D3 which inhibited ALP activity but had no significant effect on calcium metabolism. Interestingly the combination of PTH(1-34) with 1,25(OH)2D3 but not 24,25(OH)2D3 reduced calcium mobilization. The combination of the midregional fragment PTH(28-48), which by itself has no effect on calcium metabolism, with 1,25(OH)2D3 reduced calcium mobilization more efficiently. Several PTH-regulated mediators have been assayed in this system. Of the tested growth factors, IGF-I at high concentrations caused bone resorption with no effect on ALP activity. TGF-beta 1 (transforming growth factor beta) and BMP-2 had no significant effect on calcium metabolism; however, ALP activity was inhibited by TGF-beta 1 and induced dose dependently by BMP-2. Of the other factors known to be present in bone, platelet-derived growth factor (PDGFA/B) and epidermal growth factor (EGF) had a small effect on calcium mobilization but had no effect on ALP activity. bFGF reduced ALP activity slightly without an effect on calcium metabolism. Our results show that this in vitro system can mimic some interactions of calciotropic hormones in vivo and allows the assaying of mediators in terms of regulation of ALP activity and of calcium metabolism.
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PMID:Individual and combined effects of calciotropic hormones and growth factors on mineral metabolism in embryonic chick tibiae. 920 16

The modulatory effects of interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha on bone morphogenetic protein (BMP)-2- and -4-induced alkaline phosphatase (ALP) activity were examined in cultures of mouse MC3T3-E1 osteoblastic cells. Both BMP-2 and -4 significantly induced ALP in these cells. IL-1 beta alone had no effect on ALP activity, but it significantly enhanced BMP-2- and -4-induced ALP activity. TNF-alpha suppressed the induction of ALP by BMP-2 or -4. The results suggest that the action of BMP on osteogenic differentiation may be regulated by such immuno/inflammatory cytokines as IL-1 beta and TNF-alpha.
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PMID:Interleukin-1 beta enhances and tumor necrosis factor-alpha inhibits bone morphogenetic protein-2-induced alkaline phosphatase activity in MC3T3-E1 osteoblastic cells. 921 3

In serum-containing medium, ascorbic acid induces maturation of prehypertrophic chick embryo sternal chondrocytes. Recently, cultured chondrocytes have also been reported to undergo maturation in the presence of bone morphogenetic proteins or in serum-free medium supplemented with thyroxine. In the present study, we have examined the combined effect of ascorbic acid, BMP-2, and serum-free conditions on the induction of alkaline phosphatase and type X collagen in chick sternal chondrocytes. Addition of either ascorbate or rhBMP-2 to nonconfluent cephalic sternal chondrocytes produced elevated alkaline phosphatase levels within 24-72 h, and simultaneous exposure to both ascorbate and BMP yielded enzyme levels at least threefold those of either inducer alone. The effects of ascorbate and BMP were markedly potentiated by culture in serum-free medium, and alkaline phosphatase levels of preconfluent serum-free cultures treated for 48 h with BMP+ascorbate were equivalent to those reached in serum-containing medium only after confluence. While ascorbate addition was required for maximal alkaline phosphatase activity, it did not induce a rapid increase in type X collagen mRNA. In contrast, BMP added to serum-free medium induced a three- to fourfold increase in type X collagen mRNA within 24 h even in the presence of cyclohexamide, indicating that new protein synthesis was not required. Addition of thyroid hormone to serum-free medium was required for maximal ascorbate effects but not for BMP stimulation. Neither ascorbate nor BMP induced alkaline phosphatase activity in caudal sternal chondrocytes, which do not undergo hypertrophy during embryonic development. These results indicate that ascorbate+BMP in serum-free culture induces rapid chondrocyte maturation of prehypertrophic chondrocytes. The mechanisms for ascorbate and BMP action appear to be distinct, while BMP and thyroid hormone may share a similar mechanism for induction.
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PMID:Rapid chondrocyte maturation by serum-free culture with BMP-2 and ascorbic acid. 925 95

To elucidate the process of ossification in spinal ligaments, an aqueous solution containing recombinant human bone morphogenetic protein (BMP)-2 (40 micrograms/100 microL) was injected into murine ligamenta flava, and the ossification process was analyzed morphologically. In the control group, the solution administered lacked the protein; these flattened ligamentous fibroblasts possessing BMP receptors type IA and type II existed among type I collagen bundles. In the week immediately following the injection of BMP-2, ligamentous fibroblasts began to proliferate, differentiating into alkaline phosphatase-positive chondrocytes surrounded by an extracellular matrix composed of type I and II collagen. By the second week, differentiated chondrocytes of various stages were observed in type II collagen-rich matrix. These chondrocytes showed an abundance of BMP receptors type IA and II. The pathologically induced cartilage was resorbed by chondroclasts, permitting migration of blood vessels and osteogenic cells, as well as providing a site for endochondral ossification. By the third week, BMP-induced ossification had compressed the spinal cord, and by the sixth week, the ligamentous tissue had been almost completely replaced by bone. Ligamentous fibroblasts appeared to possess BMP receptors, as well as the potentiality to differentiate into chondrocytes. BMP receptors were upregulated during chondrification of ligamentous fibroblasts induced by exogenous BMP-2, suggesting that BMPs may play an important role in ossification of spinal ligaments.
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PMID:Fibroblasts of spinal ligaments pathologically differentiate into chondrocytes induced by recombinant human bone morphogenetic protein-2: morphological examinations for ossification of spinal ligaments. 926 91

Members of the transforming growth factor (TGF)-beta superfamily bind the transmembrane serine/threonine kinase complex consisting of type I and type II receptors. Their intracellular signals are propagated via respective type I receptors. Bone morphogenetic protein (BMP)-2, a member of the TGF-beta superfamily, induces ectopic bone formation when implanted into muscular tissues. Two type I receptors (BMPR-IA and BMPR-IB) have been identified for BMP-2. We have reported that BMP-2 inhibits the terminal differentiation of C2C12 myoblasts and converts their differentiation pathway into that of osteoblast lineage cells (Katagiri, T., Yamaguchi, A., Komaki, M., Abe, E., Takahashi, N., Ikeda, T., Rosen, V., Wozney, J. M., Fujisawa-Sehara, A. and Suda, T. (1994) J. Cell Biol. 127, 1755-1766). In the present study, we examined the involvement of functional BMP-2 type I receptors in signal transduction in C2C12 cells, which expressed mRNA for BMPR-IA, but not for BMPR-IB in Northern blotting. TGF-beta type I receptor (TbetaR-I) mRNA was also expressed in C2C12 cells. Subclonal cell lines of C2C12 that stably expressed a kinase domain-truncated BMPR-IA (DeltaBMPR-IA) differentiated into myosin heavy chain-expressing myotubes but not into alkaline phosphatase (ALP)-positive cells, even in the presence of BMP-2. In contrast, the differentiation of the DeltaBMPR-IA-transfected C2C12 cells into myotubes was suppressed by TGF-beta1, as in the parental C2C12 cells. BMP-2 did not efficiently suppress the mRNA expression of muscle-specific genes such as muscle creatine kinase, MyoD, and myogenin, nor did it induce the expression of ALP mRNA in the DeltaBMPR-IA-transfected C2C12 cells. In contrast, TGF-beta1 inhibited mRNA expression of the muscle-specific genes in those cells. When wild-type BMPR-IA was transiently transfected into the DeltaBMPR-IA-transfected C2C12 cells, a number of ALP-positive cells appeared in the presence of BMP-2. Transfection of wild-type BMPR-IB or TbetaR-I failed to increase the number of ALP-positive cells. These results suggest that the BMP-2-induced signals, which inhibit myogenic differentiation and induce osteoblast differentiation, are transduced via BMPR-IA in C2C12 myoblasts.
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PMID:A kinase domain-truncated type I receptor blocks bone morphogenetic protein-2-induced signal transduction in C2C12 myoblasts. 926 44


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