Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Six populations of bone cells (populations 1-6) were obtained by sequential digestion of mouse calvaria with collagenase and trypsin. After release from the tissue, each cell population was cultured for seven days. Parathormone, but not calcitonin, elicited an increase in intracellular cyclic AMP in the cells of populations 4, 5, and 6. In contrast, both hormones elicited increases in cyclic AMP in populations 2 and 3 but had no effect on population 1. When the cells of population 2 were exposed to a Falcontissue culture polystyrene surface for periods of time up to 5 min, many cells adhered. The nonadhering cell population contained a lesser proportion of cells responsive to calcitonin, whereas the adhering population contained a greater proportion responsive to this hormone. Conversely, when the cells of population 2 were exposed to an acid-treated nylon surface, the nonadhering cells contained a larger proportion of those responsive to calcitonin and a smaller proportion responsive to parathormone. When those cells that were enriched for calcitonin responsiveness were examined, we found an increased proportion that exhibited an asymmetric bipolar morphology. These differed from large amorphous, often binucleate, cells which predominated in those populations that responded exclusively to parathormone. These results establish that bone contains at least two types of target cells--one that responds to parathormone but not calcitonin, the other that responds predominantly to calcitonin.
 ...
PMID:Target cells in bone for parathormone and calcitonin are different: enrichment for each cell type by sequential digestion of mouse calvaria and selective adhesion to polymeric surfaces. 17 56

Two metabolically distinct types of bone cell populations were isolated from mouse calvaria by a repetitive digestive procedure with a mixture of collagenase and trypsin. Cells released early in the digestion showed approximately two-fold increases in cAMP when treated with either parathormone or calcitonin. These populations were denoted CT type. Later eluting cells showed larger parathormone-induced increases in cAMP but did not respond to calcitonin. These populations were denoted PT type. Six metabolic and enzymatic activites were measured in the two types of populations: acid and alkaline phosphatases, hyaluronate synthesis, citrate decarboxylation, prolyl hydroxylase, and general protein synthesis. Although each of these activites was present in both cell types, the basal levels of acid phosphatase and hyaluronate synthesis were higher in the CT cells, whereas alkaline phosphatase, citrate decarboxylation, and prolyl hydroxylase were higher in te PT cells. Parathormone stimulated acid phosphatase and hyaluronate synthesis by 100-200% only in the CT cells; in inhibited alkaline phosphatase, citrate decarboxylation, and prolyl hydroxylase by 75-90% only in the PT cells. Calcitonin alone had no effect on any of these activities other than cAMP production, but in inhibited the action of parathormone in the CT cells. The sensitivities, time courses of development,and magnitudes of these hormonal effects were similar to those observed previously in intact calvaria, indicating that the isolated cell system is a reliable model for the study of bone metabolism. Based on the metabolic responses of the cells, we postulate that the CT type of populations is enriched in osteoclasts and, possibly, osteocytes, and the PT type of population is enriched in osteoblasts.
 ...
PMID:Biochemical characterization with parathormone and calcitonin of isolated bone cells: provisional identification of osteoclasts and osteoblasts. 18 58

We have developed a preparation of monolayer cultures of bovine parathyroid cells in order to elucidate the control mechanism of the biosynthesis and secretion of parathyroid hormone (PTH) at cellular level. Dispersion of parathyroid cells was performed by stirring minced bovine parathyroid tissues in Hanks' BSS containing 0.3 yields to 0.5 percent collagenase at 37 degrees C for 60 min. Dispersed cells were cultured at 37 degrees C in MEM-Hanks' BSS containing 10 percent fetal calf serum and 15 mM HEPES. On the 5th day of the culture, the medium was replaced with 1 percent BSA-MEM-Hanks-HEPES buffer, and the cells were incubated with 3H-leucine or in the media containing various concentrations of calcium, magnesium, PGE1, PGE2 or DBcAMP. At the end of incubation, the cells were detouched and homogenized in 8M urea, 0.2 N HCL and 0.01 M cysteine solution. The isolation of proparathyroid hormone (ProPTH) and PTH was performed through the preparation of TCA-powder followed by CMC column chromatography. PTH in the incubation medium was determined by radioimmunoassay. It was demonstrated that the monolayer cultures of bovine parathyroid cells were synthesizing ProPTH and converting it to PTH. The cultures exhibited linear secretion rates of PTH into the medium. The secretion of PTH was markedly increased by PGE1, PGE2 or DBcAMP in the range of 10(-7) yields to 10(-5)M in the former and 10(-5) yields to 10(-3)M in the latter, while calcium or magnesium changed secretion rate in the range of 0.3 yields to 4.4 mM.
 ...
PMID:[Studies on the biosynthesis and secretion of parathyroid hormone in monolayer cultures of bovine parathyroid cells (I) (author's transl)]. 20 10

The preparation of dispersed parathyroid cells by collagenase digestion of porcine parathyroid glands, essentially as outlined by Brown et al. (Endocrinology 99: 1582, 1976), is described. The cells secrete parathormone linearly for at least 4 h of incubation and rapidly respond in inverse fashion to changes in the medium calcium and magnesium concentrations over the range 0.5-3.0 mM. In terms of inhibition of secretion, either ion was more effective in the presence of a minimum concentration of the other, indicating that calcium and magnesium affect separate cellular sites. Parathormone was identified both by immunoassay of the whole incubation medium and by its separation by polyacrylamide gels and carboxymethylcellulose chromatography. When the cells were incubated with radioactive amino acids and both the medium and cells were subsequently analyzed on gels, we found that parathyroid secretory protein as well as parathormone and some immunoactive fragments were present. Analysis of the radioactive protein contained in the cells at high and low calcium concentrations revealed that calcium decreased the formation of the secretory protein by approximately 40% without appreciably affecting the formation of proparathormone or parathormone. The secretion of both parathyroid secretory protein and parathormone were inversely proportional to the concentrations of medium calcium or magnesium. The secretion of the latter, however, was more sensitive (95% inhibition) than parathormone (40-60% inhibition) to changes in medium divalent cations. These results suggest that the synthesis, intracellular processing, or secretion of parathormone and parathyroid secretory protein utilize independent calcium- and magnesium-regulated pathways.
 ...
PMID:The effects of calcium and magnesium on the secretion of parathormone and parathyroid secretory protein by isolated porcine parathyroid cells. 74 33

In UMR 106 rat osteosarcoma cells, parathormone (1-34hPTH) and calcitonin (sCT) stimulated adenylate cyclase (AC) activity 5.5-and 2.8-fold, respectively. AC in osteoblasts (OB) from collagenase-treated calvaria of 3-day-old rats responded similarly to 1-34hPTH. In contrast, fibroblasts (mouse fibroblastomas) displayed a marginal 1-34hPTH sensitive AC. Osteoclasts (OC) of collagenase-treated rat calvariae, rat monocytes and mouse macrophages did not demonstrate 1-34hPTH inducable AC activity. Physiological concentrations of 24,25-dihydroxyvitamin D-3 attenuated PTH-sensitive AC in OB and UMR 106 cells within 20 min, while 1,25-dihydroxyvitamin D-3 showed no such immediate effect. In contrast, the AC response to Gpp(NH)p was unaffected by 24,25-(OH)2D3, indicating that 24,25-(OH)2D3 interrupts the coupling of the PTH receptor to the GTP binding protein Gs. OB and UMR 106 cells were also subjected to long-term (48 h) incubation with vitamin D-3 metabolites, 1-34hPTH or 20% serum from patients with secondary hyperparathyroidism (sHBT-serum), respectively. PTH-sensitive AC was markedly attenuated by pre-exposure to both 1-34hPTH and 1,25-(OH)2D3, while minimally affected by corresponding 24,25-(OH)2D3 and 20% sHPT-serum treatment. The secretion of alkaline phosphatase (Alphos) from the two cell types was strongly increased by 1-34hPTH, the effect being abolished by the presence of 24,25-(OH)2D3. Iliac crest biopsies of normal individuals exhibited a clear negative correlation between PTH-sensitive AC and corresponding serum 24,25-(OH)2D3 levels. Basal AC activity was, however, negatively correlated to serum 1,25-(OH)2D3 concentrations. In summary, the results show that 24,25-(OH)2D3 reduces PTH-stimulated AC activity in and Alphos secretion from osteoblastic bone cells by rapidly and directly interfering with the plasma membrane. These data reinforce the probable in vivo significance of 24,25-(OH)2D3. Moreover, the negative correlation between basal AC activity and serum 1,25-(OH)2D3 levels indicates a possible role for 1,25-(OH)2D3 in regulating bone cell synthesis of AC components in vivo.
 ...
PMID:1,25-dihydroxyvitamin D-3 and 24,25-dihydroxyvitamin D-3 affect parathormone (PTH) -sensitive adenylate cyclase activity and alkaline phosphatase secretion of osteoblastic cells through different mechanisms of action. 216 95

Fatty acid oxidation and its hormonal modulation were investigated in cultured rat calvaria and in cultivated cell populations. The latter were obtained from calvaria of newborn rats by sequential time-dependent digestion with collagenase, yielding eight cell populations: the early ones containing mainly fibroblasts, the middle ones being osteoblast-like, and late ones osteoblast-osteocyte-like. In calvaria, fatty acid oxidation was increased by adding 0.1 mM- and 1.0 mM-palmitate to the medium, containing 10% (v/v) fetal-calf serum. No effect was found after parathyrin addition in vitro or when injected in vivo. All cell populations obtained by sequential digestion were found to oxidize palmitate, whereby the osteoblast-like cells showed a lower oxidation rate than the other populations. Both parathyrin and calcitonin had no effect on fatty acid oxidation. 1,25-Dihydroxycholecalciferol at 1-100 nM and 24,25-dihydroxycholecalciferol at 100 nM increased oxidation primarily in the population enriched with osteoblast-like cells. Insulin at 1.6 microM diminished it in the cell populations enriched with osteoblast-like cells and in the late bone-cell fraction. However, glucagon had no effect. The energy provided by fatty acid oxidation in this system is approx. 40-80% of glucose metabolism, suggesting that this event may be of importance in the energy metabolism of bone.
 ...
PMID:Fatty acid oxidation in bone tissue and bone cells in culture. Characterization and hormonal influences. 332 35

A (sub)population of cells obtained from newborn rat calvaria by (sequential) collagenase digestion is grown to confluence in serum-containing medium. These cells are osteoblast-like with respect to high alkaline phosphatase activity and marked responsiveness (cAMP) to parathormone. Insulin-like growth factors (IGFs) enhance net incorporation of the labeled precursors thymidine, uridine, and glucose into the respective macromolecules DNA, RNA, and glycogen. Human IGF I is five times as potent as IGF II in evoking these anabolic responses in cultured rat calvaria cells. In contrast to insulin, the factors are effective in concentrations in which they are present in serum.
 ...
PMID:Insulin-like growth factors stimulate synthesis of nucleic acids and glycogen in cultured calvaria cells. 619 51

The effect of aluminum on parathyroid hormone secretion was examined using collagenase-dispersed bovine parathyroid cells. An increase in the medium aluminum concentration over the range of 0.5 to 2.0 mM, in low calcium medium, progressively inhibited the secretion of radioimmuno-assayable hormone. At 2.0 mM aluminum hormone secretion was inhibited by 68% while high medium calcium, without aluminum, maximally inhibited parathyroid hormone secretion only 39%. Individually, 2.0 mM aluminum or 2.0 mM calcium inhibited isoproterenol-stimulated hormone secretion by 43%. Either metal suppressed basal and isoproterenol-stimulated cyclic AMP levels of the parathyroid cells. That the inhibitory effect of aluminum on parathyroid hormone secretion was not due to an irreversible toxic effect was demonstrated by a restoration of normal secretion when cells were returned to 0.5 mM calcium medium without aluminum. The incorporation of [3H]leucine into total cell protein, parathyroid secretory protein, proparathyroid hormone, or parathyroid hormone was not affected by aluminum. The secretion of radiolabeled protein was, however, inhibited by aluminum. These results suggest that aluminum does not affect protein biosynthesis of the parathyroid cell or the conversion of proparathyroid hormone to parathyroid hormone. Aluminum appears to directly affect the secretion of protein from dispersed parathyroid cells.
 ...
PMID:Suppression of parathyroid hormone secretion by aluminum. 630 27