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)

We have established mutant SaOS-2 cell lines that express a cyclic AMP (cAMP)-resistant phenotype to investigate the regulation and functional importance of orthophosphoric-monoester phosphohydrolase alkaline optimum (ALPase) in the action of parathyroid hormone (PTH). Cells were stably transfected with a plasmid that directs the synthesis of a mutant form of the type I regulatory subunit of protein kinase A (PKA) under the control of the metallothionein promotor. There was no significant difference between parental SaOS-2 cells and the mutant lines in the affinity or number of receptors for 125I-Nle8,18Tyr34bPTH1-34NH2, either in the absence or presence of Zn2+. When cAMP-dependent gene transcription was examined using transient transfection with a somatostatin promoter-chloramphenicol acetyl transferase (CAT) reporter plasmid, CAT activity stimulated by human PTH and dibutyryl cAMP (DBcAMP) was inhibited by greater than 90% in the presence of Zn2+ in the mutant cell lines. In contrast, activation by a phorbol ester of a pentameric collagenase promoter/CAT construct containing five tandem copies of the AP-1 response element (5x-TRE-CAT) was unaffected in Zn(2+)-treated mutant cells. The inhibitory actions of PTH and DBcAMP on ALPase release were blunted by up to 80-90% in the mutant cell lines in the presence of Zn2+; there were no significant differences in the magnitude of inhibitory effects between these agonists. We conclude that the inhibitory action of PTH on ALPase release in SaOS-2 cells is mediated via activation of PKA. These cAMP-resistant cell lines will be especially useful in elucidating signal transduction mechanism(s) for PTH in human osteoblastic cells.
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PMID:Protein kinase A-dependent inhibition of alkaline phosphatase release by SaOS-2 human osteoblastic cells: studies in new mutant cell lines that express a cyclic AMP-resistant phenotype. 166 91

The present study examines the mechanism(s) of action of anethole trithione compared to the sialogogue pilocarpine. This was done by comparing the acute effects of these drugs on autonomic receptor binding (homogenates) together with parallel tests evaluating the biological activities of the receptor systems in collagenase-isolated rat parotid acini. The responses were measured as receptor-activated changes in cyclic nucleotide formation and acinar oxygen consumption. The results revealed that anethole trithione was unable to bind to muscarinic acetylcholine receptors and unable to stimulate the dynamic processes directly. It did, however, inhibit part (about 50%) of the carbachol-induced cyclic guanosine 3',5'-monophosphate (cyclic GMP) formation and O2 uptake. Furthermore, anethole trithione (greater than 1 microM) displaced [3H]prazosin (but not [3H]dihydroalprenolol ([3H]DHA] binding, without any effect upon the adrenaline-induced cyclic adenosine 3',5'-monophosphate (cyclic AMP) formation and O2 uptake. In conclusion, this study has shown that anethole trithione is not to be considered as a simple cholinergic agonist like pilocarpine, and further elucidation of the mechanism(s) of action of this agent would be useful.
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PMID:Acute effects of a possible sialogogue, anethole trithione, in rat parotid glands. 166 56

Human gastric mucosal cells were isolated by digestion of fundic biopsies with pronase and collagenase. The mean value of gastric cells per milligram biopsy specimen +/- SEM was 59,000 +/- 4,300 (n = 31) with a viability of 90 +/- 5%. With the cell yield of 1 patient a series of approximately 70-80 cyclic AMP measurements was possible. Histamine stimulated intracellular cyclic AMP production with an EC50 value of 35 +/- 25 mumol/l (SEM; n = 4). In the presence of 100 mumol/l histamine the Ki values (mumol/l) for the histamine H2 receptor antagonists averaged 1.45 (cimetidine), 0.10 (ranitidine), and 0.02 (famotidine). No significant inhibition of histamine-induced cyclic AMP production was obtained with the histamine H1 receptor antagonist triprolidine. With the new method histamine-induced cyclic AMP production can be measured in intact human gastric mucosal cells from fundic biopsy samples.
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PMID:A method to assess histamine-induced cyclic AMP production in isolated gastric mucosal cells from human biopsies. 168 55

When mechanical stress is applied, osteoblasts have shown to produce bone turnover stimulating hormones and enzymes like prostaglandin E2 (PGE2), cyclic AMP, alkaline phosphatase, and collagenase. Osteocalcin (bone Gla protein) is also a protein produced by osteoblasts to control bone metabolism. Thus, its production may also be stimulated by mechanical stress. The purpose of this investigation was to test if mechanical stress stimulates osteoblast-like cells to produce osteocalcin in vitro. The results suggest that osteocalcin production is stimulated at the initial stage of the culture by cyclic tension and relaxation force, and secretion may decrease with time.
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PMID:Mechanical stress as a stimulant to the production of osteocalcin in osteoblast-like cells. 181 33

1. Electrophysiological properties of the growth hormone-releasing hormone (GRH) receptor were studied in Xenopus oocytes with an intact follicle cell layer (i.e. follicular oocytes) by measuring whole-cell current using the two-electrode voltage-clamp method. 2. A slow transient outward current was elicited in oocytes, clamped at -60 mV, by the application of rat GRH but not bovine, porcine, or human GRH. 3. The response to GRH was not suppressed by blockers known to inhibit other endogenous receptors present in follicular Xenopus oocytes; blockers used were timolol (2 microM; beta-adrenergic blocker), theophylline (0.1 mM; purinergic blocker) and atropine (100 nM; muscarinic blocker). 4. The current response evoked by rat GRH occurred in a dose-dependent manner. The concentrations of GRH for threshold and maximum responses were 1 and 100 nM respectively and the estimated EC50 (half-maximal effective concentration) was approximately 7 nM. The amplitude and conductance of the response became larger and the latency, time-to-peak and half-decay time were shortened when the concentration of GRH was increased. 5. The GRH response was reversibly inhibited by a K+ channel blocker, tetraethylammonium+ (TEA+; 20 mM). The reversal potential for the GRH response was around -100 mV and was compatible with the reported value for a K+ current in Xenopus oocytes. Furthermore, a depolarizing shift of 40 mV in the reversal potential was observed when the external K+ concentration was increased from 2 to 10 mM, agreeing with the Nernst equation. In contrast, no significant shift in the reversal potential was observed by changing the external concentration of Na+ or Cl-. 6. The GRH response was not suppressed in oocytes treated with an acetoxy-methyl ester of bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA/AM; 10 microM) which penetrates the cell membrane and chelates internal Ca2+. 7. The GRH response was potentiated by pre-treatment with forskolin (0.4 microM; 5 min), which stimulates adenylate cyclase and increases the internal concentration of adenosine 3',5'-cyclic monophosphate (cyclic AMP). 8. The GRH response was not obtainable when follicle cells surrounding oocytes were removed mechanically with forceps or enzymically with collagenase (i.e. denuded oocytes). The response was also suppressed when gap junctions, which electrically couple follicle cells and the oocyte, were blocked by 1-octanol (1 mM). 9. The first amino acid is considered to be important for the binding of peptide ligands to their receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A potassium current evoked by growth hormone-releasing hormone in follicular oocytes of Xenopus laevis. 182 42

Type beta transforming growth factors represent a family of polypeptides that modulate growth and differentiation. TGF-beta exerts its effects on target cells through interaction with specific cell surface receptors, but the signal transduction pathways are largely unresolved as yet. In this study we report that TGF-beta 1 induces a rapid phosphorylation of the cyclic AMP responsive element binding protein (CREB) in mink lung CCl64 cells. Phosphorylation induced by TGF-beta 1 is not mediated by the cAMP-dependent protein kinase. Parallel to the increase in phosphorylation of CREB, an increase in binding to the collagenase TPA responsive element was observed. CREB participates in the binding to this element, probably as a heterodimer with another as yet unknown protein. The modification imposed on CREB and its involvement in an enhanced TRE-binding could be a mechanism by which TGF-beta 1 induces the TRE-mediated transcriptional activation.
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PMID:TGF-beta 1 induces phosphorylation of the cyclic AMP responsive element binding protein in ML-CCl64 cells. 185 Jun 93

The age-related evolution during fetal days 18.5-21.5 of the capacity of collagenase-dispersed Leydig cells to produce testosterone and to respond to LH or dibutyryl cyclic AMP (dcAMP) was studied in vitro in the rat. When dispersed Leydig cells were incubated in control medium, testosterone secretion by cells from 18.5-day-old fetuses during the first 5 h was 100 and 50% higher than secretion by cells from 20.5- and 21.5-day-old fetuses, respectively. The secretion maximally stimulated by 100 ng/mL LH or stimulated by 1 mM dcAMP was also stronger on day 18.5 than on days 20.5 and 21.5 during the first 3 h of culture. The dose-response curves for LH showed that the ED50 was similar for day 18.5 and 20.5 cells (2 ng/mL LH). During the course of 24-h incubation, the secretion rates also changed with time and fetal age: Between 5 and 24 h of culture basal secretion decreased in day 18.5 cells, rose slightly in day 20.5 cells, and increased sharply in day 21.5 cells; in the same way, in the presence of LH or dcAMP, the secretion by day 18.5 cells decreased faster than that of day 20.5 or 21.5 cells. The basal testosterone secretion of the Leydig cells and its maximum steroidogenic capacity decrease during late fetal life in the rat, and there was no change in the sensitivity to LH during this period. The age-related differences in the variations of the secretion rates as a function of the duration of incubation suggest the existence of an evolution in extragonadotropic regulations during late fetal life.
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PMID:Developmental changes in in vitro testosterone production by dispersed Leydig cells during fetal life in rats. 195 98

PGE2 production by glomeruli is increased in a variety of glomerular diseases. Potentially, this process may affect mesangial cell protein synthesis and mesangial cell growth. Thus studies have been undertaken, using cultured human mesangial cells, to assess the effects of PGE2 on proline uptake, protein synthesis and cell proliferation. In the presence of 140 mM NaCl, incubation of mesangial cells with 0.01 to 1 microM PGE2 for 72 hours resulted in a marked decrease of 14C proline uptake, but did not modify 14C leucine uptake. Substitution of choline to sodium inhibited 14C proline uptake by 85% which became independent of PGE2, indicating that this PG specifically altered sodium-dependent proline uptake. Inhibition of this component reached 35 to 50% with 1 microM PGE2. The inhibitory effect of PGE2 on sodium-dependent proline uptake required a lag time of 48 hours, and was suppressed by ouabain, an inhibitor of Na+, K+ ATPase activity. PGE2 did not modify the Vmax of the transport system (1.007 vs. 1.023 nmol/mg/min) but increased (P less than 0.01) its Km (1.179 vs. 0.823 mM). 8-bromo-cyclic AMP also inhibited sodium-independent proline uptake, and PGE2 markedly increased cyclic AMP production. Taken together, these results suggested that PGE2 acted via cyclic AMP stimulation. PGE2 under identical conditions (1 microM, 72 hr incubation) produced a decrease in collagen synthesis estimated by the relative rate of collagen production after incubation of mesangial cells with 14C proline (percentage of 14C radioactivity in collagenase-sensitive proteins over total proteins). PGE2 also diminished the intracellular free proline pool. More generally, PGE2 inhibited cell proliferation and cell total proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of prostaglandin E2 on proline uptake and protein synthesis by cultured human mesangial cells. 196 49

The differentiation of F9 and PSA-1 embryonal carcinoma cells to embryoid bodies composed of a mixture of parietal and visceral endoderm was accompanied by changes in their secretion of metalloproteinases. Differentiation was induced by retinoic acid and dibutyryl cyclic AMP (for F9 cells) or by removing cells from a substrate of feeder cells to alter cell-cell interaction and adhesion (for PSA-1 cells). The embryoid bodies attached to gelatin-coated dishes, and the parietal endoderm cells spread out over the matrix. The differentiated cells secreted specific gelatin- and casein-degrading proteinases, including enzymes that comigrated with proenzyme forms of collagenase and stromelysin. Total proteinase activity as well as specific collagenase activity increased with the time of differentiation. All of the gelatin- and casein-degrading proteinases detectable by substrate gel zymography were inhibited by inhibitors of metalloproteinases but not by inhibitors of serine or cysteine proteinases, indicating that they were metalloproteinases. Both cell lines showed increased collagenolytic activity, which was activated by treatment with plasmin. In addition, both cell lines showed increased secretion of specific metalloproteinase inhibitors, including tissue inhibitor of metalloproteinases, with differentiation. Analysis of mRNA from undifferentiated and differentiated F9 cells by RNA blot analysis or reverse transcription coupled with the polymerase chain reaction showed that increased expression of genes for collagenase, stromelysin and tissue inhibitor of metalloproteinases is associated with differentiation of these cells. These results suggest that the expression of extracellular matrix-degrading metalloproteinases and their inhibitors is developmentally regulated during the differentiation and spreading of the parietal endoderm.
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PMID:Expression of extracellular matrix-degrading metalloproteinases and metalloproteinase inhibitors is developmentally regulated during endoderm differentiation of embryonal carcinoma cells. 208 60

Synapsin I is a highly asymmetric neuronal structural phosphoprotein implicated in the regulation of neurotransmitter release probably by the multiple interactions it can contract with membranous and cytoskeletal elements of the neuronal cell. In order to locate the region(s) of synapsin I responsible for its association with microtubules, we have first studied synapsin I limited digestion by trypsin. The resulting polypeptides were localized in the synapsin I molecule by using three different criteria: their kinetics of appearance, their collagenase sensitivity, and the presence of the synapsin phosphorylation site 1 (cyclic AMP dependent). Synapsin I digestion kinetics are not affected by phosphorylation at this site. Analysis of the ability of various synapsin I tryptic fragments in mixture to cosediment with microtubules shows that a 44-kDa fragment corresponding to the NH2-terminal hydrophobic head of the molecule contains a binding site for polymerized tubulin. This fragment competes with native synapsin I for binding on microtubules. None of the polypeptides belonging to the tail region of synapsin I (COOH-terminal half of the molecule) were found to cosediment with microtubules.
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PMID:Limited proteolysis of synapsin I. Identification of the region of the molecule responsible for its association with microtubules. 211 98


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