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

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Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kinetic and morphologic studies in patients with parathyroid disease, and a wide variety of studies in experimental animals indicate that one major effect of PTH is to increase the proliferation of osteoprogenitor cells into osteoclasts and so to increase bone turnover. PTH stimulates bone cells by increasing cell membrane permeability to calcium and consequently increasing calcium influx and by activating membrane-bound adenyl-cyclase. It is likely that the former event precedes the latter and that calcium is the second messenger and cyclic AMP the third messenger. PTH increases the production by bone cells of lactate, citric and carbonic acids, lysosomal enzymes, collagenase, and hyaluronic acid, some or all of which are concerned in the mechanism of bone resorption. With the exception of lactate which probably comes mainly from osteocytes, the increase in metabolic activity is largely due to the increase in the number of osteoclasts. There is also ultrastructural, biochemical, and biophysical evidence that PTH stimulates existing osteoclasts, but this most likely represents the transformation of inactive cells into an active state, and is a transient and nonsustainable effect. As yet, there is no evidence that either increased osteoprogenitor cell proliferation or increased osteoclast activity is mediated by adenyl-cyclase activation. PTH also acts on the deep osteocyte to cause rapid mobilization of calcium from the zone of hypomineralized metabolically active perilacunar bone. This effect is mediated by adenyl-cyclase activation and is preceded by a slight fall in plasma calcium probably due to the movement of calcium into bone cells. The function of this rapid hypercalcemic response to PTH is correct errors in the prevailing steady-state level of plasma calcium...
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PMID:The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone diseases. II. PTH and bone cells: bone turnover and plasma calcium regulation. 18 59

Hepatocytes isolated from the liver of the common goldfish Carassius auratus L. with crude bacterial collagenase maintained ATP levels for at least 2 h. Glycogenolysis was maximally activated by 1 X 10(-6) M epinephrine and 5.8 X 10(-9) M glucagon. In liver cells incubated in calcium-free buffer containing 1 mM ethylene glycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid, basal glycogenolysis was enhanced by the addition of 1-4 mM calcium but the elevation of cyclic AMP and glycogenolysis due to epinephrine was unaffected by calcium. The divalent cation ionophore A23187 did not alter basal or hormone-stimulated glycogenolysis. Isoproterenol was approximately as potent as epinephrine but phenylephrine was glycogenolytic only at very high concentrations. l-Propranolol competitively inhibited the increased glycogenolysis due to catecholamines but phentolamine was ineffective as a blocking agent. Isoproterenol and epinephrine stimulated glycogenolysis at lower concentrations than those required to elevate cyclic AMP accumulation. Phenylephrine was without effect on cyclic AMP. Propranolol competitively inhibited both epinephrine- and isoproterenol-stimulated cyclic AMP accumulation, but phentolamine did not block either response. Catecholamine-stimulated glycogenolysis in goldfish liver is apparently a beta-adrenergic effect. However, low concentrations of epinephrine enhance glycogenolysis without affecting total cyclic AMP.
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PMID:Hormone-stimulated glycogenolysis in isolated goldfish hepatocytes. 18 9

Parenchymal rat liver cells were isolated by the collagenase method and incubated in Krebs-Henseleit buffer containing 0.5% gelatin. The basal level of cyclic AMP in isolated cells was 0.52 nmol per g liver wet wt. Glucagon (10(-10)-10(-6) M) caused a significant increase in the level of cyclic AMP. Maximum levels were obtained 2-15 min after addition of glucagon. Repeated administration of glucagon caused a new increase in cyclic AMP, but the response was lesser than after the first addition of glucagon, indicating refractoriness to glucagon. The rate of albumin secretion was 4.6 mug/min per g liver wet wt. This is about the rate found in the perfused liver, Glucagon (10(-8-10(-6) M) inhibited albumin secretion and the incorporation of 14C-leucine into albumin, into total proteins in the medium and into total proteins in the cell suspension. The effect of glucagon on albumin secretion is compatible with an effect on the rate of synthesis. A positive correlation existed between the maximal level of cyclic AMP after glucagon administration and the inhibition of both albumin secretion and the incorporation of 149leucine.
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PMID:Effect of glucagon on cyclic AMP, albumin metabolism and incorporation of 14C-leucine into proteins in isolated parenchymal rat liver cells. 18 84

An LH-responsive Leydig cell preparation (containing 6+/-2% Leydig cells) was obtained by collagenase treatment of rat testis. Centrifugation of this cell preparation through a 13% Ficoll solution for 10 min at 1500 g resulted in a four times purification of the Leydig cells, with a concomitant increases in steroidogenic activity. Addition of 0-2% albumin to the 13% Ficoll solution, adjusted to 280 mosmol/l, resulted in a further twofold purification of the Leydig cells paralleled by a twofold increase in steroidogenic activity. Centrifugation of these Ficoll-albumin-purified Leydig cells through a 6% dextran solution for 2 min at 100 g resulted in a further 1-7 times purification of the Leydig cells. A combination of the two centrifugation steps resulted in a 12-5 times purification of Leydig cells compared with the original crude cell suspension, while an increase in steroidogenic activity of 22-5 times was obtained. This final cell preparation contained 59 +/- 17% Leydig cells (mean +/- S.D., n = 6). The recovery of Leydig cells was 29%. Collagenase treatment of testes deficient in spermatogenesis resulted in a cell preparation with the same steroidogenic activity as Ficoll-purified cells from normal testes. Centrifugation of these cells through a 13% Ficoll solution gave only a limited increase in the steroidogenic activity. Isopycnic centrifugation of the crude cell preparation on a discontinous Ficoll metrizoate gradient resulted in two discrete peaks of Leydig cells, one peak at a density of 1-039-1-055 g/ml and one at a density of 1-068-1-088 g/ml. Both types of cells produced testosterone. In the presence of LH, cyclic AMP production in both types of Leydig cells increased, but testosterone production was only increased by LH in the "denser" Leydig cells and not in the "light" Leydig cells. No difference in sensitivity to LH could be observed between the Leydig cell preparations of different purity. Using a 60 min pre-incubation period the highest testosterone response was obtained with 100-1000 ng LH/ml. The same maximum testosterone response was obtained with 10-100 ng LH/ml when the pre-incubation period was omitted.
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PMID:Purification and characterization of Leydig cells from rat testes. 18 9

Choriogonadotropin and lutropin have been found to activate cyclic AMP-dependent protein kinase in ovarian cells isolated by collagenase dispersion from immature rats. The stimulatory effect of gonadotropins was dependent on both hormone concentration and incubation time. Choriogonadotropin at 1 mug/ml fully stimulated the protein kinase activity within 5 min of incubation, and this effect was specific for choriogonadotropin and lutropin-like activity. In addition, protein kinase activity has been characterized with respect to salt sensitivity, cyclic AMP binding, and its responsiveness to gonadotropins and other peptide hormones. Ovarian protein kinase was susceptible to high salt concentrations. The addition of 0.3-1.0 M-NaCl in incubation medium increased the activity ratio with a concomitant decrease in cycle AMP-dependence. The salt effect on protein kinase was observed both from hormone-treated and untreated cells. The hormone-stimulated and unstimulated protein kinase activity was completely stable in the absence of NaCl. No change in the activity ratio was observed when cellular extracts were assayed for protein kinase activity either immediately or after 2 h in the absence of added salt. Gel filtration in the absence of NaCl of cellular extracts prepared from choriogonadotropin-treated and untreated cells showned only a single peak of protein kinase activity that was sensitive to exogenously added cyclic AMP. By contrast, when 0.5 M-NaCl was included in the column buffer, the chromatography of untreated extract showed two peaks of protein kinase activity. The first peak was sensitive to added cyclic AMP, whereas the second peak was insensitive to it. Under identical experimental conditions, protein kinase from gonadotropin-treated cells showed, on gel filtration, only one peak of activity that was totally insensitive to added cyclic AMP. DEAE-cellulose column chromatography of a 20000 g supernatant fraction resulted in a peak of kinase activity that eluted in approx. 0.15 M-NaCl, similar to the similar to the elution of type II protein kinases as described by Corbin et al. (1975) (J. Biol. Chem. 250, 218-225). Choriogonadotropin stimulation produced a decrease in the capacity of protein kinase to bind exogenous cyclic [3H]AMP, with a concomitant increase in the kinase activity ratio. These results are consistent with the notion that cyclic AMP, GENERATED IN SITU Under hormonal stimulation, binds tot he regulatory subunit of protein kinase with subsequent dissociation of the active catalytic subunit from the holoenzyme.
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PMID:Ovarian adenosine 3':5'-cyclic monophosphate-dependent protein kinase(s). Regulation by choriogonadotropin and lutropin in rat ovarian cells. 18 32

1. A method is described for the isolation of rat parotid acinar cells by controlled digestion of the gland with trypsin followed by collagenase. As judged by Trypan Blue exclusion, electron microscopy, water, electrolyte and ATP concentrations and release of amylase and lactate dehydrogenase, the cells are morphologically and functionally intact. 2. A method was developed for perifusion of acinar cells by embedding them in Sephadex G-10. Release of amylase was stimulated by adrenaline (0.1-10muM), isoproternol (1 or 10 MUM), phenylephrine (1 muM), carbamoylcholine (0.1 or 1 muM), dibutyryl cycle AMP (2 MM), 3-isobutyl-1-methylxanthine (1mM) and ionophore A23187. The effects of phenylephrine, carbamoylcholine and ionophore A23187 required extracellular Ca2+, whereas the effects of adrenaline and isoproterenol did not. 3. The incorporation of 45Ca into parotid cells showed a rapidly equilibrating pool (1-2 min) corresponding to 15% of total Ca2+ and a slowly equilibrating pool (greater than 3h) of probably a similar dimension. Cholinergic and alpha-adrenergic effectors and ionophore A23187 and 2,4-dinitrophenol increased the rate of incorporation of 45Ca into a slowly equilibrating pool, whereas beta-adrenergic effectors and dibutyryl cyclic AMP were inactive. 4. The efflux of 45Ca from cells into Ca2+-free medium was inhibited by phenylephrine and carbamoylcholine and accelerated by isoproterenol, adrenaline (beta-adrenergic effect), dibutyryl cyclic AMP and ionophore A23187. 5. A method was developed for the measurement of exchangeable 45Ca in mitochondria in parotid pieces. Incorporation of 45Ca into mitochondria was decreased by isoproterenol, dibutyryl cyclic AMP or 2,4-dinitrophenol, increased by adrenaline, and not changed significantly by phenylephrine or carbamoylcholine. Release of 45Ca from mitochondria in parotid pieced incubated in a Ca2+-free medium was increased by isoproterenol, adrenaline, dibutyryl cyclic AMP or 2,4-dinitrophenol and unaffected by phenylephrine or carbamoylcholine. 6. These findings are compatible with a role for Ca2+ as a mediator of amylase-secretory responses in rat parotid acinar cells, but no definite conclusions about its role can be drawn in the absence of knowledge of the molecular mechanisms involved, their location, and free Ca2+ concentration in appropriate cell compartment(s).
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PMID:Calcium metabolism and amylase release in rat parotid acinar cells. 18 53

(1) In order to determine the cellular localization of the secretin- and pancreozymin-sensitive adenylate cyclase in rat pancreas, the occurence of this enzyme system has been investigated in isolated pancreatic cells. (2) Digestion of rat pancreatic lobules with collagenase yields a preparation of isolated cells which upon differential morphological analysis appears to consist for 97% of acinar cells and to contain for fewer centro-acinar and ductal cells than undissociated lobules. (3) Expressed per mg protein, the isolated cells contain the same amount of DNA, chymotrypsin and lactic dehydrogenase as the undissociated tissue. The stimulated adenylate cyclase activity is nearly entirely recovered in the isolated acinar cells, as is also the case for the low Km adenosine 3',5-cyclic monophosphate phosphodiesterase activity and the adenosine 3',5'-cyclic monophosphate (cyclic AMP) content. Marked losses are noted for the basal adenylate cyclase and the high Km cyclic AMP phosphodiesterase activities. (4) Washing the isolated acinar cells in Krebs-Ringer bicarbonate medium containing 10 mM 1-methyl-3-isobutylxanthine causes a cyclic AMP level 2.6 times that in cells washed in Krebs-Ringer bicarbonate alone. The cyclic AMP level is further increased by subsequently incubating the cells for 10 min in the presence of 3-10(-7) M pancreozymin-C-octapeptide or secretin to values 1.7 or 4.7 times the control level in cells incubated for 10 min with 1-methyl-3-isobutylxanthine alone. (5) It is suggested that the adenylate cyclase of the acinar cells may be involved, with another factor, in the stimulation of enzyme secretion, whereas a ductular cyclase would function in the regulation of the bicarbonate-dependent fluid secretion.
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PMID:Rat pancreas adenylate cyclase V. Its presence in isolated rat pancreatic acinar cells. 18 46

In order to explore the distribution of hormone-responsive cells in skeletal tissues, we have examined the effects of synthetic bovine parathyroid hormone N-terminal peptide (bPTH 1-34) and salmon calcitonin (sCT) on cyclic AMP levels in periosteum-free rat calvaria, segments of periosteum, and in isolated cells dispersed from each tissue by collagenase digestion. Synthetic bovine PTH increased cyclic AMP levels to a greater degree in calvaria and in isolated bone cells than in the periosteal segments and cells, whereas sCT was more effective in the periosteal than in the bone systems. Primary cultures prepared from bone and periosteal cell populations exhibited progressive increases in their responsiveness to bPTH (1-34) and progressive decreases in responsiveness to sCT. After six days in the culture, bone cells failed to respond to sCT, and sCT did not modify their response simultaneously added bPTH (1-34). Six-day periosteal cell cultures exhibited residual sCT responsivity and an additive response upon simultaneous exposure to high concentrations of bPTH (1-34) and sCT suggesting separate sites of hormone action. Adenosine, a known stimulator of bone cell adenylyl cyclase, caused a greater increase in periosteal cell than in bone cell cyclic AMP. bPTH (1-34)-responsive cells which enrich periosteum-free bone may be osteoblasts, in view of their histological prominence in this tissue and in the bone cell isolates. Periosteal cells which responded to sCT and to adenosine preferentially are unidentified. Although periosteal segments contained numerous fibroblast-like cells, skin fibroblasts cultured from the same fetuses were sCT-insensitive. Growth in primary culture appears to alter the number of hormone-responsive cells or responsiveness of existing cells to each hormone, or both.
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PMID:Evidence for preferential effects of parathyroid hormone, calcitonin and adenosine on bone and periosteum. 19 Dec 42

The effects of somatostatin on insulin release and cyclic AMP metabolism were studied in collagenase-isolated islets of Langerhans from the rat. Ceoncentrations from 500 to 2000 ng/ml significantly inhibited glucose stimulated insulin release, while 100 and 200 ng/ml were ineffective. Somatostatin (2000 ng/ml) inhibited insulin release and [3H]-cyclic AMP accumulation induced by 16.7 mM glucose after 10 and 30 min of incubation. In dose-response studies, the inhibition by somatostatin of the effect of glucose on [3H]cyclic AMP and insulin release could be overcome by a high concentration of the hexose (44.9 mM), suggesting competitive inhibition. In the absence of glucose, somatostatin inhibited [3H]cyclic AMP accumulation induced by the phosphodiesterase inhibitor, IBMX, while no inhibition was seen, again in the absence of hexose, when the [3H]cyclic AMP levels had been raised by the adenyl cyclase stimulator, cholera toxin. Somatostatin did not affect phosphodiesterase activity when added to islet homogenates, but preincubation of the islets with the peptide before homogenization decreased the activity by about 30%. It is suggested that somatostatin-induced inhibition of insulin release is, at least partially, mediated by cyclic AMP, probably through an action on islet adenyl cyclase.
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PMID:Studies on the mechanisms of somatostatin action on insulin release. IV. effect of somatostatin on cyclic AMP levels and phosphodiesterase activity in isolated rat pancreatic islets. 19 42

In order to study the role of cyclic AMP in the inhibition by somatostatin of glucose-induced insulin release, the effect of somatostatin on the potentiation by dibutyryl-cyclic AMP (db-cAMP) of insulin release from isolated pancreatic islets of rats was examined. Isolated islets were obtained from the rat pancreas by the collagenase method. Ten islets were incubated for periods of 30 min in Krebs-Ringer bicarbonate buffer containg albumin and glucose 2.0 mg/ml in the presence or absence of somatostatin (1 microgram/ml or 100 ng/ml) and/or db-cAMP 1 mM. Glucose-induced insulin release was reduced by somatostatin in concentrations of 1 microgram/ml. Somatostatin in a concentration of 100 ng/ml significantly abolished the potentiation by db-cAMP of insulin release (p less than 0;01), in spite of exerting no inhibition of glucose-induced insulin release. However, in the presence of theophylline 5 mM, somatostatin 100 ng/ml did not show that inhibitory effect on the potentiated insulin release.
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PMID:Insulin release from collagenase-isolated islets of rat pancreas in the presence of cyclic AMP and somatostatin. 20 May 35


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