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)

Collagenolytic enzyme release from bone cells was studied using cultured calvarial cells which are capable of degrading calcified and noncalcified collagen (cells from normal mice) or only noncalcified collagen (cells from osteopetrotic (mi/mi) mice). Treatment of cells from either normal or mi/mi mice with parathyroid hormone (PTH) or lipopolysaccharide (LPS) resulted in the appearance of latent collagenolytic enzyme activity in the medium. Chromatography of media from cells from normal mice treated with PTH on lysine-Sepharose resulted in the separation of latent collagenase and latent gelatinase. Further characterization of the enzymes showed that they were similar to those previously isolated from media of calvaria cultured with heparin. Collagenase activity of media of cells from normal or mi/mi mice treated with PTH or LPS yielded identical elution patterns upon chromatography on lysine-Sepharose. These results show that the mi allele has no effect on regulation of latent collagenolytic enzyme release. The results show that the mi allele has no effect on regulation of latent collagenolytic enzyme release. The data also suggest that previously described differences between PTH- and LPS-stimulated collagen degradation in cultured calvaria are due to factors other than differences in the ability of these agents to stimulate the release of collagenolytic enzymes.
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PMID:Stimulation of collagenolytic enzyme release from cultured bone cells of normal and osteopetrotic (mi/mi) mice by parathyroid hormone and lipopolysaccharide. 254 66

Proximal tubules were prepared from rat kidney cortex by collagenase digestion and purified by Percoll gradient centrifugation. Their enrichment was estimated by comparing the specific activities of various cell-specific enzymes in homogenates of renal cortex and of the isolated tubules. The tubules were cultured in a 50:50 mixture of Dulbecco's modified Eagle's and Ham's F12 media supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, and prostaglandin E1. After 2 to 3 d an extensive outgrowth of epithelial cells developed from the attached tubules. After 5 to 7 d near confluent monolayers were obtained. Hormonal responsiveness, marker enzyme activities, and transport properties were determined to further characterize the primary cultures. The cultured cells exhibited increased cyclic AMP production in response to parathyroid hormone but not calcitonin or vasopressin, consistent with the absence of cells derived from distal and collecting tubules. The cells also retained significant levels of 25-hydroxyvitamin D3-1 alpha-hydroxylase, alkaline phosphatase, and gamma-glytamyl-transpeptidase, three enzymes that are primarily associated with the proximal tubule. The cultured epithelial cells also exhibit a Na+-dependent phosphate and glucose transport systems. Therefore, the cells retain many functional properties that are characteristic of proximal tubules. Thus, the primary cultures should be suitable for the study of processes that occur specifically within this segment of the rat nephron.
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PMID:Characterization of primary cell cultures derived from rat renal proximal tubules. 254 89

Bovine parathyroid tissue was evaluated as a model to compare parathyroid hormone-related peptide (PTH-rP) and parathyroid hormone (PTH) secretion. Tissue was incubated in variable calcium levels (n = 5). A parathyroid cell digest was prepared from collagenase-treated glands. PTH-rP and PTH levels were determined by radioimmunoassay. PTH-rP bioactivity was determined by 3H-cAMP production in a UMR 106 cell bioassay. PTH-rP levels in the incubation medium were 2.0 ng/mg protein (0.25 mmol Ca++), 2.2 ng/mg protein (1.25 mmol Ca++), and 1.9 ng/mg protein (2.5 mmol/L Ca++). PTH levels were 321 ng/mg protein (0.25 mmol/L Ca++) and 200 ng/mg protein (2.5 mmol Ca++). Therefore, calcium significantly inhibited PTH but not PTH-rP secretion (p = 0.03). Addition of incubation medium to the bioassay resulted in 3H-cAMP levels that were 8 to 10 times greater than basal levels. Greater than 50% of the activity persisted after addition of PTH antibody, demonstrating that a significant amount of the activity was caused by PTH-rP. Tissue PTH-rP was 5.1 ng/mg protein, compared with 2080 ng/mg protein for PTH. We conclude that (1) bovine parathyroid tissue contains bioactive PTH-rP and is a useful model to compare the biosynthesis and secretion of PTH-rP and PTH in normal tissue and (2) unlike PTH, PTH-rP secretion is not regulated by calcium.
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PMID:Bovine parathyroid tissue: a model to compare the biosynthesis and secretion of parathyroid hormone and parathyroid hormone-related peptide. 255 27

Collagenolytic enzyme activity associated with the noncalcified pool of collagen was studied using calvarial matrices from which the periosteal cell envelope had been removed. Aminophenylmercuric acetate (APMA) stimulated degradation of about 5% of the noncalcified collagen in matrices prepared from freshly dissected bone. Significantly more activity was detected if intact calvaria were cultured 24 h before removal of the cells, in which case 20-30% of the noncalcified collagen was degraded following treatment with APMA. Trypsin elicited a similar response. The collagen being degraded was representative of the entire pool of noncalcified collagen and was not underhydroxylated. Treatment of intact calvaria with parathyroid hormone (PTH) before removal of the cells increased the level of both active collagenase and procollagenase activity associated with the matrix. Enhanced 3H release was noted for PTH treated intact bone in the prior 24 h. Inactivation of endogenous procollagenase by phenanthroline had no effect on the ability of isolated calvarial cells to resorb the bone upon treatment with resorptive agents. The data show that PTH-stimulated collagenolysis of noncalcified collagen involves increased deposition of procollagenase onto the noncalcified matrix in addition to activation of the enzyme.
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PMID:Procollagenase associated with the noncalcified matrix of bone and its regulation by parathyroid hormone. 255 74

The influence of phorbol myristate acetate (PMA), an activator of protein kinase c, on the secretion of parathyroid hormone from collagenase-dispersed bovine parathyroid cells was tested. The cells were incubated at low (0.5 mM) or high (2.0 mM) concentrations of calcium in the medium, and the hormone secreted into the medium was measured by a radioimmunoassay that recognizes both intact and C-terminal fragments of hormone. At low calcium, the secretory rate averaged 32 +/- 3.8 ng.h-1.(10(5) cells)-1. The addition of 1.6 microM PMA did not affect secretion. At high calcium there was a significant suppression of secretion by 38% to 19.8 +/- 3 ng.h-1.(10(5) cells)-1. The addition of 1.6 microM PMA significantly stimulated hormone secretion to 35.8 +/- 8 ng.h-1.(10(5) cells)-1, a rate indistinguishable from low calcium. This stimulatory effect of PMA at high calcium was seen at PMA concentrations as low as 1.6 nM, did not occur with a biologically inactive 4 alpha-isomer of phorbol ester, and was independent of changes in cellular adenosine 3',5'-cyclic monophosphate levels. Examination of 32P-labeled phosphoproteins by two-dimensional gel electrophoresis revealed acidic proteins of approximately 20,000 and 100,000 Da that were phosphorylated at low and high calcium + 1.6 microM PMA but not at high calcium alone. The protein kinase c activity associated with the membrane fraction of parathyroid cells significantly decreased 40% when the cells were incubated at high vs. low calcium. The data suggest that calcium may regulate parathyroid hormone secretion through changes in protein kinase c activity of the membrane fraction of the cell and protein phosphorylation.
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PMID:Effect of phorbol myristate acetate on secretion of parathyroid hormone. 282 13

Monensin, a monovalent cation ionophore, inhibited collagenase production in mouse osteoblast-rich bone cell and clonal osteogenic cell cultures. Inhibition of parathyroid hormone-stimulated bone resorption by monensin was also studied in calvaria cultures. Collagenase activity levels in the medium decreased concomitantly with the inhibition of bone resorption by monensin, indicating that monensin inhibited bone resorption by blocking collagenase secretion from osteoblasts in bone explants.
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PMID:Monensin inhibits collagenase production in osteoblastic cell cultures and also inhibits both collagenase release and bone resorption in mouse calvaria cultures. 299 87

Human bone cell cultures were established by maintaining collagenase-treated bone fragments in low Ca++ medium. The resulting cell cultures exhibited a high level of alkaline phosphatase activity and produced a significant increase in intracellular cAMP when exposed to the 1-34 fragment of human parathyroid hormone. With continued culture, the cells formed a thick, extracellular matrix that mineralized when cultures were provided daily with normal levels of calcium, fresh ascorbic acid (50 micrograms/ml) and 10 mM beta-glycerol phosphate. Biosynthetically, these cells produced type I collagen (without any type III collagen), and the bone-specific protein, osteonectin. In addition, the cells produced sulfated macromolecules electrophoretically identical to those positively identified as the bone proteoglycan in parallel cultures of fetal bovine bone cells. This technique provides a useful system for the study of osteoblast metabolism in vitro.
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PMID:Human bone cells in vitro. 299 72

Monoclonal antibodies have been produced against primary bone cells obtained from the collagenase digestion of mouse cranial bone. Antibodies were selected on the basis of their immunoglobulin class and those which were identified as IgG were further screened for their ability to inhibit cAMP accumulation in response to sub-maximal doses of the 1-34 amino-terminal peptide of bovine parathyroid hormone, bPTH(1-34). Nine hybridoma clones were subsequently characterized as inhibitory with respect to parathyroid hormone (PTH) responses in intact mouse cranial bone and which also identified a variety of membrane components from detergent extracts of surface-labeled primary bone cells. Five of these antibodies immunoprecipitated a membrane component with Mr of 80 000 that appeared to be a major component of the extract susceptible to surface-labeling with 125I. All nine monoclonal antibodies were shown to bind to a suspended-cell preparation of primary bone cells with 2-3 orders of magnitude greater binding than that of control antibodies. Using this assay, one clone, designated 3G12 IgG, was observed to exhibit desensitization effects at the binding level with a time course and dose dependency for PTH pre-incubation that was similar to the establishment of the refractory state in other systems. In addition, the desensitization effect occurred at 37 degrees C but not at 4 degrees C. This antibody was shown to bind saturably to both intact mouse cranial bone and primary bone cells with an apparent affinity constant (Ka) in the range of 10(9) M. Inhibition of bone cAMP accumulation in response to 2.5 nM bPTH(1-34) was directly correlated to the binding of 3G12 IgG to intact mouse calvariae. A maximum inhibition of approximately 85% was observed. 3G12 IgG immunoprecipitated a single membrane component, Mr 150 000, from NP-40 detergent extracts of 125I-labeled primary mouse bone cells. The molecular mass of this component was also 150 000 daltons when run on polyacrylamide gel slabs under non-reducing conditions. Control and PTH-pre-treated bone cells were surface-labeled, detergent-solubilized and immunoprecipitated with 3G12 IgG in order to investigate further the desensitization effect at the molecular level. Incubation of bone cells with 1 microgram/ml bPTH(1-34) for 45 min at 37 degrees C caused an increased susceptibility to surface-labeling with 125I that was approximately three-fold higher in specific activity than that of control cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Identification of a 150-kDa membrane component which is modulated by parathyroid hormone. 299 91

When added to cultures of parathyroid hormone (PTH)-stimulated bones, dichloromethylenebisphosphonate (C12MBP) and 3-amino-1-hydroxypropydilene-1,1-bisphosphonate (AHPrBP) inhibit completely and in a parallel manner the development of resorption lacunae, the loss of calcium by the explants and their PTH-induced excretion of lysosomal hydrolases (beta-glucuronidase and N-acetyl-beta-glucosaminidase). The loss of collagen (hydroxyproline) by the bones is usually less inhibited than their loss of calcium and their heparin-induced excretion of collagenase is unaffected. To interpret these data, it is proposed that these bisphosphonates act more on the activity of osteoclasts, suppressing simultaneously their excretion of lysosomal enzymes and their erosion of mineralized bone matrix, than on that of other cell types (osteoblasts ?) responsible for collagenase production and the removal of uncalcified collagen.
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PMID:Bisphosphonates and bone resorption: effects on collagenase and lysosomal enzyme excretion. 299 48

A specific and potent synthetic inhibitor of mammalian tissue collagenase and related metallo-proteinases inhibits the collagen matrix resorption induced by parathyroid hormone (PTH) in cultured embryonic mouse calvaria. The inhibition is reversible, dose-dependent and virtually complete at 50 microM inhibitor concentration whereas that due to a less potent stereoisomer is much weaker. The PTH-enhanced secretion of calvarial lysosomal enzymes and the small spontaneous leakage of lactate dehydrogenase are not affected by the inhibitor. These results suggest that collagenase plays a critical role in bone resorption. Its role is discussed in relation to that of cysteine-proteinases that have also been implicated in this process.
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PMID:A new synthetic inhibitor of mammalian tissue collagenase inhibits bone resorption in culture. 300 46


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