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 MC3T3-E1 mouse calvaria-derived cell line has been used to study the role of collagen synthesis in osteoblast differentiation. MC3T3-E1 cells, like several previously characterized osteoblast culture systems, expressed osteoblast markers and formed a mineralized extracellular matrix only after exposure to ascorbic acid. Mineralization was stimulated further by beta-glycerol phosphate. Ultrastructural observations indicated that the extracellular matrix produced by ascorbic acid-treated cells was highly organized and contained well-banded collagen fibrils. Expression of osteoblast markers followed a clear temporal sequence. The earliest effects of ascorbic acid were to stimulate type I procollagen mRNA and collagen synthesis (24 h after ascorbate addition), followed by induction of alkaline phosphatase (48-72 h) and osteocalcin (96-144 h) mRNAs. Procollagen mRNA, which was expressed constitutively in the absence of ascorbate, increased only twofold after vitamin C addition. In contrast, alkaline phosphatase and osteocalcin mRNAs were undetectable in untreated cultures. Actions of ascorbic acid on osteoblast marker gene expression are mediated by increases in collagen synthesis and/or accumulation because (1) parallel dose-response relationships were obtained for ascorbic acid stimulation of collagen accumulation and alkaline phosphatase activity, and (2) the specific collagen synthesis inhibitors, 3,4-dehydroproline and cis-4-hydroxyproline, reversibly blocked ascorbic acid-dependent collagen synthesis and osteoblast marker gene expression.
...
PMID:Relationship between collagen synthesis and expression of the osteoblast phenotype in MC3T3-E1 cells. 137 31

We characterized gene expression in the reparative callus that formed after fracture of the rat femur. The callus was divided into regions of bone formation (hard callus) and cartilage formation (soft callus), and gene expression was examined separately in each region. Expression of extracellular matrix protein genes varied with the progression of repair and differed between hard and soft calluses. Messenger ribonucleic acids (mRNAs) for osteonectin, alkaline phosphatase, and type I procollagen were detected in the hard callus at maximal levels during endochondral ossification and bone remodeling (day 15) and at 50% maximal levels during intramembranous bone formation (day 7). Messenger RNAs for these proteins in the soft callus were detected at low levels during chondrogenesis (day 9) but increased to 80% of maximal levels with chondrocyte hypertrophy and mineralization of the cartilage matrix (day 13). Messenger RNAs for type II procollagen and proteoglycan core protein were detected at maximal levels in the soft callus during chondrogenesis (day 9). Osteocalcin gene expression was detected in the hard callus during endochondral ossification and remodeling but not during intramembranous bone formation or at any time in the soft callus. Osteonectin mRNA was detected in both the hard and soft callus throughout the entire course of fracture repair. Expression of cartilage and bone-related genes correlated with the temporal sequence of histologic changes, suggesting transcriptional regulation of gene expression during repair. Differences in gene expression between hard and soft callus and in each of these regions as repair progressed suggest local regulation of gene expression during cell differentiation and matrix synthesis.
...
PMID:Genetic expression of extracellular matrix proteins correlates with histologic changes during fracture repair. 141 97

The effects of inhaled glucocorticoids on serum markers of bone formation were evaluated in asthmatic children. Serum total alkaline phosphatase (AP), bone alkaline phosphatase (BAP), osteocalcin, and the novel marker of bone formation, carboxypropeptide of type I procollagen (PICP), were measured. In the cross-sectional part, long-term glucocorticoid users were compared with sodium cromoglycate (SCG) users. In the boys (n = 16), but not in the girls (n = 11), PICP was significantly lower in the glucocorticoid users than in the SCG users. PICP correlated positively with BAP (n = 54; groups combined, r = 0.29, p < 0.05). In the longitudinal part, the effects of inhaled budesonide or SCG, both used for the first time, were evaluated before and after 1 and 5 months of treatment. The budesonide dose was 800 micrograms/m2/day for 1 month and thereafter half of that. The SCG dose was 30 mg/day throughout the study. Only during budesonide use did osteocalcin and PICP decrease, the median osteocalcin by 8% at 1 month (p < 0.05) and by 6% at 5 months (n = 15), and PICP by 5% at 1 month (p < 0.05) and by 28% at 5 months (n = 7, p < 0.01). AP and BAP did not change significantly. Decreased PICP suggests decreased bone formation rate. PICP might be clinically useful as a marker of early adverse effects of glucocorticoids on bone.
...
PMID:Effects of inhaled budesonide on serum markers of bone metabolism in children with asthma. 143 Jul 6

We measured type I procollagen carboxyl-terminal propeptide (PICP) by a commercial radioimmunoassay and amino-terminal propeptide (PINP) by an enzyme-linked immunosorbent assay (ELISA) developed in our laboratory in serum from 75 normal women, 10 growing girls, 84 normal men, and 197 patients with various metabolic bone diseases. The molar concentrations of serum PINP were 100-fold higher than those of PICP, suggesting differences in the metabolism of PICP and PINP. In normal women, serum PICP values correlated positively with age and serum PINP values correlated negatively with age (r = 0.28 and -0.32, respectively; P = 0.02). In normal men, however, PICP correlated negatively with age (r = -0.32, P = 0.003) whereas PINP did not change. As assessed by Z scores (SD from age- and sex-specific predicted normal mean), changes in serum PICP and PINP values were concordant in hypoparathyroidism (mean Z scores for PICP and PINP, -0.63 and -1.48, respectively) and Cushing's syndrome (0.50 and 0.40) but were discordant in acromegaly (0.78 and -0.68), hyperthyroidism (1.33 and -0.66), untreated postmenopausal osteoporosis (-0.11 and 0.40), fluoride-treated postmenopausal osteoporosis (-0.61 and 1.08), Paget's disease (4.05 and -0.20), and chronic renal failure (1.45 and -0.50). With either assay, deviations from normal were less pronounced than the deviations of concurrently measured serum osteocalcin and bone alkaline phosphatase values. The deviations in these latter two values agreed better with those of PICP than with those of PINP, except in untreated or fluoride-treated osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Utility of type I procollagen propeptide assays for assessing abnormalities in metabolic bone diseases. 146 50

To investigate the role of transforming growth factor-beta 1 (TGF beta) in bone metabolism, the effects of this agent on the differentiation characteristics of human bone cells were studied in vitro. Human bone cells were isolated from femoral head samples by collagenase digestion. Differentiation characteristics included alkaline phosphatase activity, osteocalcin production, and mRNA levels for alkaline phosphatase, type I alpha 2-procollagen, and osteocalcin. The effect of TGF beta on alkaline phosphatase was not constant, but varied with the incubation conditions. At high cell density and in the presence of serum, TGF beta decreased alkaline phosphatase activity. However, at low cell density and under serum-free conditions, TGF beta stimulated alkaline phosphatase activity. The addition of 1,25(OH)2 vitamin D3 also stimulated alkaline phosphatase. The combination of the two agents gave a greater increase in activity than the sum of the activities when the two agents were given alone. The percentage of cells that stain positively for alkaline phosphatase changed in parallel with the change in specific activity. The percentage of positive cells increased from 17% to 64%, while the specific activity increased from 22 to 169 mU/mg protein. To investigate the mechanism of this stimulation, mRNA levels were measured at 24 hours. Individually, TGF beta and 1,25(OH)2D3 increased message levels for alkaline phosphatase and type I procollagen, but the greatest effect was produced by the combination of the two factors. 1,25(OH)2D3 increased osteocalcin mRNA levels, but TGF beta markedly inhibited this stimulation. TGF beta also inhibited production of osteocalcin by the human bone cells. TGF beta appears to modulate differentiation of human bone cells in combination with 1,25(OH)2D3 and other factors.
...
PMID:Differentiation of normal human bone cells by transforming growth factor-beta and 1,25(OH)2 vitamin D3. 153 45

Since it has been suggested that gastric resections are followed by changes in bone metabolism, the aim of our study was to determine the biochemical parameters of bone metabolism and radial and lumbar bone density in 15 male ulcus patients treated by partial gastrectomy (Billroth II). Comparing the data with those of a corresponding control group, the lumbar bone density measured by quantitative computed tomography was statistically significantly lower (P less than 0.04) in the patient group, whereas the peripheral bone mass of the distal part of the nondominant forearm measured by single-photon absorptiometry showed no statistically significant difference. In addition, a marked increase in alkaline phosphatase (P less than 0.002) and urinary excretion of hydroxyproline (P less than 0.003) was found in gastrectomy group, whereas the 25-hydroxy-vitamin D levels were found to be significantly decreased (P less than 0.04). Osteocalcin, a biochemical marker for osteoblast activity, and the carboxy-terminal propeptide of type I procollagen (PICP), a marker of collagen formation, were slightly but not significantly higher in gastrectomy-treated patients. The serum parathyroid hormone levels were similar in both groups. As none of the patients had any radiologic evidence of osteopenia, the changes in biochemical parameters of bone metabolism and bone mass in patients who had undergone partial gastrectomy could be a marker of latent bone loss.
...
PMID:The influence of partial gastrectomy on biochemical parameters of bone metabolism and bone density. 160 Mar 54

This study compares the synthesis of mutant type I collagen in cultured dermal fibroblasts and trabecular osteoblasts that were isolated from a patient with moderately severe osteogenesis imperfecta (type IV). Previous study of this patient's dermal fibroblasts revealed a 2000 dalton deletion located in cyanogen bromide peptide 4 of alpha 2(I)-collagen. The phenotype of the bone cell cultures was defined by a 3-4 day logarithmic phase doubling time, predominantly type I collagen production over type III and alkaline phosphatase activity 13.5 times dermal fibroblast levels. The current study revealed that both fibroblasts and osteoblasts synthesized a normal and a shortened alpha 2(I) chain, each as the product of separate alleles. Following pepsin treatment of the procollagens, a shortened alpha 1(I) chain was also seen in both cell types. Cyanogen bromide peptide mapping of osteoblast alpha-chains demonstrated the same deletions in the cyanogen bromide peptide 4 as observed in the fibroblast cyanogen bromide maps. PAGE analysis of oligonucleotide-specific cDNA that was reverse transcribed from RNA isolated from fibroblasts and osteoblasts also demonstrated the presence of two bands, one the normal size of alpha 2(I) cDNA and a second species that was smaller by 54 base pairs. Sequencing of polymerase chain reaction-amplified cDNA fragments revealed an in-frame deletion of exon 12. This finding was confirmed by the RNase protection method. Genomic DNA sequencing detected a T----G point mutation in the second position of the 5' splice donor site of intron 12. Therefore, in this patient with osteogenesis imperfecta there was no qualitative alteration in the osteoblast-specific expression of this mutant alpha 2(I)-collagen allele compared to dermal fibroblasts.
...
PMID:Expression of mutant alpha (I)-procollagen in osteoblast and fibroblast cultures from a proband with osteogenesis imperfecta type IV. 164 48

Estrogen stimulates osteoblastic collagen production in vitro, but whether the same stimulation takes place in vivo is still unknown. To test the stimulatory effects of a combined estrogen-gestagen regimen in vivo we monitored serum levels of the carboxy-terminal propeptide of human type I procollagen (S-PICP) in a group of 12 osteoporotic women over a 150 week treatment period. Spinal bone mineral content (BMC) increased to a maximum of 5% over pretreatment values around week 90. Serum alkaline phosphatase (S-AP) and serum bone gla protein (S-BGP) both fell from initial values of 220 U/liter and 39 ng/ml, respectively, to 146 U/liter (p less than 0.01) and 27.2 ng/ml (NS) around week 60 and remained reduced over the remaining treatment period. S-PICP also fell from 117 to 68 micrograms/liter at week 60 and 70 micrograms/ml at week 150 (P less than 0.01). This is equal to a reduction to 32 +/- 10% pretreatment levels. The reduction in S-PICP was not significantly different from that of the other two markers of bone formation (S-AP and S-BGP). Thus, provided the metabolic clearance of PICP remains unaltered after hormone replacement therapy, no major stimulation of osteoblastic collagen type I synthesis was demonstrable during estrogen-gestagen treatment in this population of osteoporotic women. The changes in bone markers seen in this study are therefore consistent with an estrogen-mediated reduction in the frequency of remodeling activation. Because of the reduction in bone turnover and methodologic limitations of bone marker assays, however, smaller increases in the amount of bone formed per activation could remain undetectable.
...
PMID:Effects of a combined estrogen-gestagen regimen on serum levels of the carboxy-terminal propeptide of human type I procollagen in osteoporosis. 172 40

Two new bone cell lines were established by immortalizing cells derived from embryonic rat calvariae with a recombinant retrovirus containing the cDNA for SV-40 large T antigen and the neomycin resistance gene. One cell line, RCT-1, isolated from early digest cells, a population which typically does not express osteoblastic features, displayed osteoblastic characteristics only after 3 days of treatment with 1 microM retinoic acid: alkaline phosphatase activity increased from 0.003 to 0.25 mumol/min.mg protein, the steady state level of type I procollagen mRNA increased 4-fold, and the cells acquired a PTH-stimulatable adenylate cyclase (EC50, 10 nM). mRNA for osteopontin, an abundant bone matrix protein, was induced in RCT-1 cells by 1,25-dihydroxyvitamin D3 (10 nM). The second cell line, RCT-3, isolated from late digest cells, a population previously shown to be enriched with differentiated osteoblasts, expressed constitutively the properties described above. In addition, RCT-3 cells responded to interleukin-1 by increased prostaglandin production (EC50, 20 pM) and to prostaglandin E2 by enhanced cAMP accumulation, features exhibited by calvarial cells in organ culture. Thus, the SV-40 immortalized cell lines we describe retained many of the characteristics of osteoblasts in primary culture, including hormonal regulation of phenotype-related genes. In RCT-1 cells the coordinate induction of several properties by retinoic acid offers a new model for the study of differentiation-related gene expression in bone cells.
...
PMID:Rat calvarial cell lines immortalized with SV-40 large T antigen: constitutive and retinoic acid-inducible expression of osteoblastic features. 247 May 84

Acidic fibroblast growth factor (aFGF) and basic FGF (bFGF) are related molecules that are extractable from bone matrix and may be important in the maintenance of normal bone physiology. The influence of each agent on DNA and protein synthesis was studied using bone-derived primary cell cultures. Both forms of FGF were relatively more mitogenic for bone cell populations with fewer osteoblastic (Ob) characteristics than for Ob-enriched cultures. However, in the Ob cultures, bFGF was intrinsically 10-fold more stimulatory than aFGF, whereas heparin enhanced the mitotic response only to aFGF. An optimal dose of either aFGF or bFGF (100 ng/ml) decreased alkaline phosphatase activity and increased the rate of noncollagen and collagen protein synthesis in Ob cultures. The stimulatory effect was relatively greater on noncollagen than on collagen synthesis, which resulted in a decrease in percent collagen synthesis. Neither factor altered the rate of collagen degradation. Furthermore, hydroxyurea diminished, but did not prevent, the stimulatory effect of each factor on rates of protein synthesis. In contrast, polyacrylamide gel analysis of newly synthesized protein and Northern blot analysis of steady state alpha 1 type I procollagen mRNA indicated differential effects by each agent on procollagen synthesis and processing. These studies suggest that the FGFs may produce their effects on Ob cells through both shared and disparate mechanisms, with the net result being a decrease in the expression of the osteoblastic phenotype.
...
PMID:Effects of fibroblast growth factors on deoxyribonucleic acid and collagen synthesis in rat parietal bone cells. 279 81


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

---