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

---

Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The bone morphogenetic proteins (BMPs) and transforming growth factor-beta s (TGF-beta s), are a group of structurally related proteins which have been shown to stimulate bone formation in vivo. Since these proteins are concentrated in the organic matrix of bone and would be released during bone resorption, they are likely to have a profound effect on the remodeling bone and may provide a link between bone resorption and bone formation. We are using primary cultures of fetal rat calvarial cells (FRCC) to study the independent and combined effects of OP-1/BMP-7 and TGF-beta 1 on bone cells at different stages of differentiation in order to identify responding cell populations and target genes. We have confirmed prior reports that OP-1 stimulates, while TGF-beta 1 inhibits, osteogenic differentiation in this system. The increase in both number and size of the mineralized nodules induced by OP-1 was accompanied by increased expression of alkaline phosphatase and type I collagen with an induction of bone sialoprotein (BSP) suggesting that OP-1 stimulates both differentiation and clonal expansion of osteoblastic cells. Interestingly, TGF-beta 1 abrogated OP-1 induced nodule formation. Despite these opposing effects on osteogenic differentiation, TGF-beta 1 (Wrana et al, 1991) and OP-1 both stimulated a rapid induction of osteopontin (OPN) mRNA in confluent FRCC cultures enriched in pre-osteoblastic cells. In contrast, when OP-1 was added to nodule-forming cultures which are enriched in osteoblastic cells, there was only a weak induction of OPN. Moreover, while the expression of one marker for mature osteoblasts (BSP) was refractory to OP-1, another (osteocalcin) was markedly stimulated. Thus OP-1 has selective effects on bone matrix protein expression that are dependent on the differentiated state of the cells.
...
PMID:Influence of osteogenic protein-1 (OP-1;BMP-7) and transforming growth factor-beta 1 on bone formation in vitro. 908 44

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.
...
PMID:Interaction between soluble type I receptor for bone morphogenetic protein and bone morphogenetic protein-4. 911 Oct 68

Bone morphogenetic protein-2 (BMP-2), a member of transforming growth factor-beta superfamily, inhibits the terminal differentiation of C2C12 myoblasts and changes their differentiation pathway into cells expressing osteoblast phenotypes such as alkaline phosphatase (ALP) activity and osteocalcin production (Katagiri et al., 1994, J. Cell Biol. 127, 1755-1766). Two type I receptors for BMP-2 (BMPR-IA and BMPR-IB) have been cloned, but the role of the respective receptors in signal transduction is not clear. In the present study, we examined the signal transduction of BMP-2 in C2C12 cells using constitutively activated mutant BMPR-IA and BMPR-IB. C2C12 cells expressed BMPR-IA and BMPR-II mRNAs, but not BMPR-IB mRNA at detectable levels in Northern blotting. When mutated BMPR-IA and BMPR-IB were transiently transfected into C2C12 cells, both BMPR-IA and BMPR-IB similarly induced ALP activity in the absence of BMP-2. We also established subclonal cell lines of C2C12 cells by stably transfecting mutated BMPR-IB. When the mutated BMPR-IB-transfected cells were cultured in medium with low serum (differentiation medium) without BMP-2, the cells differentiated into ALP-positive mononuclear cells and not into myosin heavy chain-positive myotubes. These mutated BMPR-IB-transfected cells expressed ALP activity and osteocalcin mRNA in a time-dependent manner, but neither muscle creatine kinase nor myogenin mRNAs. These results indicate that the mutated BMP-2 type I receptors can constitutively transduce BMP-2 signals in the absence of the ligand in C2C12 cells.
...
PMID:Constitutively active BMP type I receptors transduce BMP-2 signals without the ligand in C2C12 myoblasts. 929 60

The purpose of this study is to differentiate roles of several growth factors and cytokines in proliferation and differentiation of pulp cells during development and repair. In human pulp cell cultures, laminin and type I collagen levels per cell remained almost constant during the whole culture period (22 days). On the other hand, secreted protein, acidic and rich in cysteine (SPARC/osteonectin) and alkaline phosphatase (ALPase) levels markedly increased after the cultures reached confluence. Laminin and type I collagen, as well as fibronectin, stimulated the spreading of pulp cells within 1 h. Adding transforming growth factor-beta (TGF-beta) decreased laminin and ALPase levels, whereas it increased SPARC and fibronectin levels 3- to 10-fold. Western and Northern blots showed that TGF-beta enhanced SPARC synthesis at the protein and mRNA levels. Basic fibroblast growth factor (bFGF) decreased type I collagen, laminin, SPARC, and ALPase levels without changing the fibronectin level. Platelet-derived growth factor (PDGF) selectively decreased laminin, SPARC, and ALPase levels. Epidermal growth factor (EGF) also decreased SPARC and ALPase levels. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) decreased type I collagen and laminin levels, and abolished SPARC and ALPase syntheses. Of these peptides, bFGF and PDGF showed the greatest stimulation of [3H]thymidine incorporation into DNA. TGF-beta, EGF, and TNF-alpha had less effect on DNA synthesis, whereas IL-1beta inhibited DNA synthesis. These findings demonstrated that TGF-beta, bFGF, EGF, PDGF, TNF-alpha, and IL-1beta have characteristically different patterns of actions on DNA, laminin, type I collagen, fibronectin, ALPase, and SPARC syntheses by pulp cells.
...
PMID:Differential effects of various growth factors and cytokines on the syntheses of DNA, type I collagen, laminin, fibronectin, osteonectin/secreted protein, acidic and rich in cysteine (SPARC), and alkaline phosphatase by human pulp cells in culture. 942 6

Since the bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta (TGF-beta) superfamily that induce the differentiation of mesenchymal precursor cells into the osteogenic cells, we identified the relevant signaling molecules responsible for mediating BMP-2 effects on mesenchymal precursor cells. BMP-2 induces osteoblastic differentiation of the pluripotent mesenchymal cell line C2C12 by increasing alkaline phosphatase activity and osteocalcin production. As recent studies have demonstrated that cytoplasmic Smad proteins are involved in TGF-beta superfamily signaling, we plan to isolate the relevant Smad family members involved in osteoblastic differentiation. We identified human Smad5, which is highly homologous to Smad1. BMP-2 caused serine phosphorylation of Smad5 as well as Smad1. In contrast, TGF-beta failed to cause serine phosphorylation of Smad1 and Smad5. We found Smad5 is directly activated by BMP type Ia or Ib receptors through physical association with these receptors. Following phosphorylation, Smad5 bound to DPC4, another Smad family member, and the complex was translocated to the nucleus. Overexpression of point-mutated Smad5 (G419S) or a C-terminal deletion mutant DPC4 (DPC4 delta C) blocked the induction of alkaline phosphatase activity, osteocalcin production, and Smad5-DPC4 signaling cascades upon BMP-2 treatment in C2C12 cells. These data suggest that activation of Smad5 and subsequent Smad5-DPC4 complex formation are key steps in the BMP signaling pathway, which mediates BMP-2-induced osteoblastic differentiation of the C2C12 mesenchymal cells.
...
PMID:Smad5 and DPC4 are key molecules in mediating BMP-2-induced osteoblastic differentiation of the pluripotent mesenchymal precursor cell line C2C12. 944 19

1. The effect of zinc compounds on bone components in the femoral-metaphyseal tissues from elderly female rats (50 weeks old) was investigated in vitro. Bone tissues were cultured for 24 hr in Dulbecco's modified Eagle medium containing either vehicle or zinc compounds (10[-7] to 10[-5] M). 2. Zinc content, alkaline phosphatase activity, deoxyribonucleic acid (DNA) and calcium contents in the metaphyseal tissues were significantly increased by the presence of zinc sulfate (10[-6] and 10[-5] M), beta-alanyl-L-histidinato zinc (AHZ; 10[-6] and 10[-5] M) and zinc acexamate (10[-7] to 10[-5] M). At 10[-5] M, the effect of zinc acexamate on the increase of bone components was more potent than that of zinc sulfate or AHZ. 3. The effect of zinc acexamate (10[-5] M) on the increase of alkaline phosphatase activity in the metaphyseal tissues was remarkable as compared with that of insulin (10[-8] M), estrogen (10[-9] M), insulin-like growth factor-I (10[-8] M), transforming growth factor-beta (10[-10] M), sodium fluoride (10[-3] M), dexamethasone (10[-7] M) and vitamin K2 (menaquinone-4; 10[-5] M) with an effective concentration. 4. The stimulatory effect of zinc acexamate (10[-5] M) on alkaline phosphatase activity and calcium content in the metaphyseal tissues was completely blocked by the presence of dipicolinate (10[-3] M), a chelator of zinc ion, and of cycloheximide (10[-6] M), an inhibitor of protein synthesis. 5. The present study demonstrates that zinc acexamate has a potent anabolic effect on bone components in the femoral-metaphyseal tissues from female elderly rats in vitro. The effect of zinc acexamate may be based in part on protein synthesis related to zinc ion in bone cells.
...
PMID:Potent effect of zinc acexamate on bone components in the femoral-metaphyseal tissues of elderly female rats. 951 97

The decrease in bone volume associated with osteoporosis and age-related osteopenia is accompanied by increased marrow adipose tissue formation. Reversal of this process may provide a novel therapeutic approach for osteopenic disorders. We have shown that cells cultured from human trabecular bone are not only osteogenic, but are able also to undergo adipocyte differentiation under defined culture conditions. Osteoblast differentiation was induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and adipocyte differentiation by dexamethasone (dex) plus 3-isobutyl-1-methylxanthine (IBMX) treatment. Adipogenesis was characterized by lineage-specific enzyme and gene activities, alpha-glycerophosphate-3-dehydrogenase activity, fatty acid binding protein, aP2 and lipoprotein lipase expression. Osteoblastogenesis was assessed by osteoblast characteristic 1,25(OH)2D3 induction of alkaline phosphatase activity and osteoblast-specific 1,25(OH)2D3-induced osteocalcin synthesis and release. We provide evidence for a common pluripotent mesenchymal stem cell that is able either to undergo adipogenesis or osteoblastogenesis, using clonal cell lines derived from human trabecular bone cell cultures. Adipogenesis can be induced also by long chain fatty acids and the thiazolidinedione troglitazone. Dex plus IBMX-induced adipogenesis can be inhibited by interleukin-1beta, tumor necrosis factor-alpha, and transforming growth factor-beta. Interestingly, and in contrast to extramedullary adipocyte differentiation as shown by mouse 3T3L-1 and a human liposarcoma SW872 cell line, trabecular bone adipogenesis was unaffected by insulin. Also, the formation of fully differentiated adipocytes from trabecular bone cells after troglitazone treatment and long chain fatty acids was dependent on increased expression of the nuclear hormone receptor peroxisome proliferator-activated receptor gamma2 caused by dex plus IBMX. Specific inhibition of marrow adipogenesis and promotion of osteoblastogenesis of a common precursor cell may provide a novel therapeutic approach to the treatment of osteopenic disorders.
...
PMID:Human trabecular bone cells are able to express both osteoblastic and adipocytic phenotype: implications for osteopenic disorders. 952 37

Human osteoblastic cells were grown in a three-dimensional (3-D) cell culture model and used to test the effects of a 20 Hz sinusoidal electromagnetic field (EMF; 6 mT and 113 mV/cm max) on collagen type I mRNA expression and extracellular matrix formation in comparison with the effects of growth factors. The cells were isolated from trabecular bone of a healthy individual (HO-197) and from a patient presenting with myositis ossificans (MO-192) and grown in a collagenous sponge-like substrate. Maximal enhancement of collagen type I expression after EMF treatment was 3.7-fold in HO-197 cells and 5.4-fold in MO-192 cells. Similar enhancement was found after transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) treatment. Combined treatment of the cells with EMF and the two growth factors TGF-beta and IGF-I did not act synergistically. MO-192 cells produced an osteoblast-characteristic extracellular matrix containing collagen type I, alkaline phosphatase, and osteocalcin, together with collagen type III, TP-1, and TP-3, two epitopes of an osteoblastic differentiation marker. The data suggest that the effects of EMFs on osteoblastic differentiation are comparable to those of TGF-beta and IGF-I. We conclude that EMF effects in the treatment of skeletal disorders and in orthopedic adjuvant therapy are mediated via enhancement of collagen type I mRNA expression, which may lead to extensive extracellular matrix synthesis.
...
PMID:Effects of extremely low frequency electromagnetic field (EMF) on collagen type I mRNA expression and extracellular matrix synthesis of human osteoblastic cells. 958 65

Bone loss is observed after exposure to weightlessness in both astronauts and inflight animals. Histological and biochemical studies on rats have shown a decrease in bone formation, probably as a result of altered osteoblast function. To investigate whether microgravity alters osteoblast differentiation in vitro, the human osteosarcoma cell line MG-63 was used as a model. MG-63 cells can be induced to differentiate by treating the cells with 1,25(OH)2D3 (10(-7) mol/L) and transforming growth factor-beta 2 (TGFbeta2) (10 ng/mL). The message level of differentiation-related genes was quantitated via competitive reverse transcription-polymerase chain reaction (RT-PCR), both in untreated and hormone-treated cells cultured under microgravity for 9 days aboard the unmanned Foton 10 spaceflight, and compared to ground and inflight unit-gravity cultures. At microgravity, gene expression for collagen Ialpha1 following treatment was reduced to 51% of unit-gravity levels (p < 0.05). The amount of alkaline phosphatase messenger ribonucleic acid (mRNA) following treatment at microgravity increased by only a factor of 5 compared to the tenfold increase at unit gravity (p < 0.02). The osteocalcin message level in treated cells cultured at microgravity was only 19% of the level found in cells grown at unit gravity (p < 0.02). In conclusion, microgravity reduces the differentiation of osteoblastic MG-63 cells in response to systemic hormones and growth factors.
...
PMID:Gene expression related to the differentiation of osteoblastic cells is altered by microgravity. 960 Jul 71

During postnatal development, the formation of new blood vessels is possible only through angiogenesis. The initial growth of solid neoplasms, including childhood brain tumors, during the genetically determined stages of carcinogenesis, even at clinically undetectable sizes (a few mm3), depends upon the continuous formation of new blood capillaries [i.e. neovascularization (NV)/neoplasm-related angiogenesis (NRA)]. The generation of a malignant, invasive cellular immunophenotype (CIP) and distant metastases are also NRA-dependent processes. Endothelial cells undergo rapid proliferation during brain tumor related angiogenesis. Human endoglin (CD105/EDG), is a homodimeric cell surface component of the transforming growth factor-beta (TGF-beta) type I receptor complex and is also a proliferation-associated antigen (PAA) expressed at high density on endothelial cells. Formalin fixed, paraffin-wax embedded (3-5 microns thick), as well as frozen tissue sections (6 microns thick) of 62 childhood brain tumors [34 medulloblastomas (MEDs) and 28 astrocytomas (ASTRs)], were employed for the assessment of EDG expression. Both an indirect, four-step, alkaline phosphatase (AP) conjugated, biotin-streptavidin based (or a diamino-benzidine [DAB]) conjugated immunoperoxidase antigen detection technique were employed, utilizing the SN6h anti-EDG monoclonal antibody (DAKO Corp.). Another antigen detection method, based on the Histogold (Zymed) reaction was also employed using the same antibody on formalin fixed, paraffin-wax embedded tissues. Strong expression (A; +3 to +4) of EDG on endothelial cells and demonstrated in all 62 childhood brain tumor cases. The most striking feature of the newly formed tumor-related capillaries was the presence of a markedly enlarged perivascular space. Blood vessels in several normal human tissues (cortex, cerebellum, thymus, tonsil, spleen, lymph node, skin) used as control tissues contained significantly lower levels of EDG (B and mostly C; +/- to +), in accordance with the extremely slow turnover rate of normal endothelial cells. A close apposition between the capillaries and the adjacent parenchyma was also observed. Brain tumors, especially glioblastoma, are among the most vascularized human neoplasms, and thus are candidates for antiangiogenic therapy. VEGF/PF-R1 (flt-1) and VEGF/PF-R2 (flk-1) are formed de novo in a glioma progression-dependent manner. Further studies should substantiate the importance of EDG in the earliest possible detection, diagnosis and NRA inhibition-based treatment of mammalian solid neoplasms, especially childhood brain tumors.
...
PMID:Upregulation of endoglin (CD105) expression during childhood brain tumor-related angiogenesis. Anti-angiogenic therapy. 967 60


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---