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)

The cell-free endocranial surface of young adult rat parietal bones was used as a substrate for osteoclastic bone resorption, either without prior treatment, or after incubation of the parietal bones with collagenase or neonatal rat calvarial cells. Untreated, the endocranial surface consisted of unmineralized organic fibres; incubation with calvarial cells or collagenase caused disruption and removal of these fibres, with extensive exposure of bone mineral on the endocranial surface, without morphologically detectable mineral dissolution. Neonatal rabbit osteoclasts resorbed bone to a greater extent from parietal bones pre-incubated with calvarial cells or collagenase than from untreated bones; mineral exposure and subsequent osteoclastic resorption were both increased if calvarial cells were incubated with parathyroid hormone; removal of bone mineral after incubation with calvarial cells removed the predisposition to osteoclastic resorption. These experiments demonstrate that calvarial cells are capable of osteoid destruction, and indicate that one mechanism by which osteoblasts induce osteoclastic bone resorption may be through digestion of the unmineralized organic material that covers bone surfaces, to expose the underlying resorption-stimulating bone mineral to osteoclastic contact.
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PMID:Bone cells predispose bone surfaces to resorption by exposure of mineral to osteoclastic contact. 406 84

Latent collagenase was isolated by heparin-Sepharose affinity chromatography from the culture medium of clonally derived mouse osteogenic (MC3T3-E1) cells. Collagenase synthesis by MC3T3-E1 cells was significantly stimulated by the addition of parathyroid hormone to the serum-containing culture medium. The cellular origin of the isolated collagenase was confirmed by demonstrating the characteristic 3/4 and 1/4 fragments of collagen alpha-chain, as well as inhibition of the enzyme by anti-mouse bone collagenase antibody.
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PMID:Osteoblast collagenase: collagenase synthesis by clonally derived mouse osteogenic (MC3T3-E1) cells. 608 36

Two cell populations were isolated from calvaria of chick embryos: PF cells were liberated by collagenase treatment from the periosteum, OB cells from the periosteum-free calvarium. Both populations were cultured in plastic culture dishes. After 6 d of culture, monolayers of each cell type either were scraped off the culture dishes, transplanted on the chorio-allantoic membrane of 7-d-old quail eggs, and cultured there for 6 d, or were used for biochemical experiments. OB transplants proved capable of producing calcified bone matrix, whereas PF transplants formed only fibrous tissue. Biochemically, OB cells showed high cAMP production in the presence of parathyroid hormone (PTH), whereas cAMP production was not stimulated in PF cultures. Lactate production was stimulated by PTH in both populations although somewhat differently. Citrate decarboxylation was high in OB cells and was inhibited by PTH but was low in PF cells, where it was stimulated by the same hormone. The differences in hormonal response between the two cell types made it possible to conclude that PF cultures are relatively free of OB cells. The PF contamination in OB cultures was more difficult to assess. The experiments described in this report show that the OB population contains osteoblasts or osteoblastlike cells which are, under favorable circumstances, capable of bone formation.
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PMID:Bone formation and calcification by isolated osteoblastlike cells. 617 44

Studies on the direct effects of hormones and growth factors on bone alkaline phosphatase have been limited to parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D3 [1,25(OH)2D3] and have not been compared to other parameters of bone formation. Insulin, PTH, 1,25(OH)2D3, epidermal and fibroblast growth factors (EGF, FGF) were examined for their effects on alkaline phosphatase activity and type I, [alpha 1 (I)]2 alpha 2, collagen synthesis in cultures of 21-day fetal rat calvariae. After 24 hr and 96 hr of treatment, insulin increased whereas PTH, 1,25(OH)2D3, EGF and FGF inhibited calvarial alkaline phosphatase activity and the incorporation of 3H-proline into collagenase-digestible protein and type I collagen. The agents tested did not affect the release of alkaline phosphatase into the culture medium. Although type I collagen was the only collagen detected, a small amount of another collagen might have been also synthesized. The hormonal effects on alkaline phosphatase activity and type I collagen synthesis were of greater magnitude after 96 hr than after 24 hr of continuous exposure to the agents tested and the two parameters correlated well (r = 0.88 after 96 hr and r = 0.97 after 24 hr of treatment. These studies indicate that insulin increases bone alkaline phosphatase activity and type I collagen synthesis in calvariae whereas PTH, 1,25(OH)2D3, EGF and FGF have an inhibitory effect. The results suggest that these agents affect osteoblastic function.
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PMID:Effect of hormones and growth factors on alkaline phosphatase activity and collagen synthesis in cultured rat calvariae. 621 95

Insulinlike growth Factor I (IGF I), a growth hormone-dependent peptide or somatomedin, was studied for its effects on bone formation by examining the synthesis of DNA, collagen, and noncollagen protein in cultures of 21-d fetal rat calvaria. IGF I caused a dose-dependent stimulation of the incorporation of [3H]thymidine into DNA at concentrations of 0.1--100 nM; the effect appeared after 6 h, was maximal at 12 h, and was sustained for 96 h. IGF I also increased the bone DNA content, IGF I at 0.1--3 nM had a small stimulatory effect on the incorporation of [3H]proline into collagenase-digestible protein (CDP) whereas 30 nM IGF I caused a two- to threefold increment and had a maximal effect. A smaller effect on the labeling of noncollagen protein (NCP) was also observed. The effect of CDP and NCP appeared and was maximal after 12 h and was sustained for 96 h. IGF I increased the total collagen content of bones. The IGF I stimulatory effect on the incorporation of [3H]thymidine was seen in both the periosteum and periosteum-free calvarium, whereas that on the labeling of CDP was seen only in the central, osteoblastic-rich, non-periosteal bone. Histological sections showed a 10-fold increase in the mitotic index after Colcemid arrest in IGF I-treated bones, the mitoses were equally distributed in the periosteum and central portions of the calvarium. Insulin had a stimulatory effect on the incorporation of [3H]proline into CDP and NCP and 1 nM--1 microM similar to the effect of IGF I. In contrast, high insulin concentrations (0.1 and 1 microM) were required to increase the incorporation of [3H]thymidine, and insulin did not affect DNA content. Cortisol decreased the stimulatory effect of IGF I on DNA labeling but greatly enhanced the stimulatory effect of IGF I on the incorporation of [3H]proline into CDP. Triiodothyronine and parathyroid hormone increased the incorporation of [3H]thymidine and were additive to IGF I. Triiodothyronine did not affect the labeling of CDP, but parathyroid hormone inhibited it and opposed the effect of IGF I. These studies indicate that IGF I stimulates bone DNA, collagen, and NCP synthesis in vitro. IGF I and insulin have similar effects on bone collagen synthesis but IGF I stimulates the synthesis of DNA at physiological concentrations, and insulin does not.
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PMID:Effect of insulinlike growth factor I on DNA and protein synthesis in cultured rat calvaria. 625 49

The structural requirements for the inhibition of net bone collagen synthesis by parathyroid hormone (PTH) in vitro have been examined by study of the effects of selected fragments and analogs of bovine PTH (bPTH) upon the incorporation of [3H]proline into collagenase-digestible and -nondigestible proteins by neonatal mouse calvarial bone in organ culture. At concentrations of 10(-10)-10(-7) M, the amino-terminal fragment bPTH-(1-34) was found to be as potent as intact bPTH in the specific suppression of net bone collagen synthesis after 24 h in culture. The synthetic fragments bPTH-(1-30), bPTH-(1-28), and bPTH-(3-34) were approximately 3%, 1%, and 0.2% as active, respectively, as bPTH-(1-34), in good agreement with previous estimates of the relative potencies of these hormonal fragments on bone resorption in vitro and in vivo and on adenylate cyclase activation in and receptor binding to isolated renal membranes. The amino-terminal analog [Ser1]bPTH-(1-34) displayed no reduction in biological activity compared with bPTH-(1-34), as previously found for bone resorption in vivo. The overall results with this assay system indicate a minimum sequence for biological activity that extends from residues 3-28 of intact bPTH, which is consistent with similar estimates in other test systems and emphasizes the importance of the aminoterminus of the hormone in the expression of its biological effects on bone formation as well as resorption. Moreover, these findings support the potential usefulness of the mouse calvarial culture system in predicting the skeletal activity in vivo of new synthetic analogs of PTH.
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PMID:Bone collagen synthesis in vitro: structure/activity relations among parathyroid hormone fragments and analogs. 625 80

1. Active mouse bone collagenase is excluded from its inhibitory antibody by preincubation of that antibody with various forms of inactive enzyme, e.g. 'procollagenase', some collagenase-inhibitor complexes or partially denatured or degraded collagenase. This property allows the detection of several enzymatically inactive forms of collagenase. 2. The accumulation of immunoreactive collagenase in the culture fluid of mouse bones occurred only in the presence of heparin and was not correlated with bone resorption induced by parathyroid hormone. These experiments provide further (see Lenaers-Claeys, G. and Vaes, G., Biochim. Biophys. Acta (1979) 584, 375-388), more conclusive evidence that the critical role in the resorption of the organic matrix of these explants may be due to another enzyme system than collagenase.
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PMID:Immunoreactive collagenase and bone resorption. 625 50

Hormone-dependent adenylate cyclase activity was measured separately in the different nephron portions by combining the microdissection of collagenase-treated rabbit kidneys and the use of a single tubule enzyme microassay. The results obtained in the rabbit for vasopressin, parathyroid hormone, calcitonin, and isoproterenol are given and discussed. Each hormone stimulated adenylate cyclase activity in several well-localized segments of tubule according to a highly specific and reproducible pattern. Sharp transitions were generally noted between responsive and unresponsive nephron portions. In the rat kidney, the functional segmentation of the distal convoluted tubule was not as clearly delineated as in the rabbit kidney. Various nephron segments of the rat kidney were observed to contain glucagon-sensitive adenylate cyclase activity. When the results obtained for vasopressin are compared in rabbit, rat, mouse, and human kidneys, species differences are noted with respect to the responsiveness to arginine vasopressin in the medullary portion of thick ascending limbs of Henle's loops. It is concluded that biochemical approaches can be used as a means of investigating problems dealing with kidney physiology very near the cell level.
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PMID:Sites of hormone action in the mammalian nephron. 625 51

Supernatant fluids from the cultures of bone marrow cells from 10 of 12 patients with multiple myeloma (MM) caused bone resorption in organ cultures of fetal rat calvaria. In four patients, the marrow cells were cultured with and without indomethacin (1 muM). The supernatant fluids from indomethacintreated marrow cultures caused significantly less bone resorption than supernatant fluids of cell cultures without indomethacin. This inhibition of release of bone resorbing factor(s) by myeloma cultures is similar to the previously observed indomethacin-induced inhibition of osteoclast-activating factor (OAF) production by activated human leukocytes. None of the MM supernatants had any effect on cyclic (c)AMP accumulation in resorbing bone in vitro. Four separate preparations of partially purified OAF obtained from phytohemagglutinin-stimulated peripheral human leukocytes were tested for their ability (a) to cause bone resorption in organ cultures of fetal rat and neonatal mouse calvaria and (b) to cause accumulation of cAMP in rat and mouse skeletal tissue in vitro. Those dilutions of OAF that caused bone resorption had no effect on accumulation of cAMP in rat or mouse calvaria incubated in vitro. In addition, no stimulation of adenylate cyclase activity in membranes prepared from fetal rat calvaria could be found. Bone cell populations isolated by sequential collagenase digestion of fetal rat calvaria also showed no cAMP response to these dilutions of OAF. Parathyroid hormone caused a clear response in all three systems. Furthermore, no cAMP response to OAF was observed in calvaria in the presence of cholera toxin (1 mug/ml) and isobutyl-methylxanthine (0.3 mM). These observations demonstrate that (a) supernatant fluids from MM marrow cultures stimulate bone resorption but do not increase cAMP accumulation in vitro; (b) indomethacin interferes with the release of bone resorbing factors by MM bone marrow cultures suggesting that this process requires prostaglandins; and (c) Sephadex G100 or G75 purified OAF does not stimulate adenylate cyclase or increase cAMP accumulation at equivalent bone resorbing concentrations in rat and mouse skeletal tissue. The resorptive action of MM culture fluids is similar to that of partially purified OAF from activated cultured leukocytes, but different from those of other bone resorbing factors, parathyroid hormone and prostaglandin E(2), which stimulate cAMP production in skeletal tissue.
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PMID:Observations on the mechanism of bone resorption induced by multiple myeloma marrow culture fluids and partially purified osteoclast-activating factor. 626 78

Effects on Ca2+ transport of parathyroid hormone (PTH) and N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate (DB-cAMP) were examined in the rabbit distal nephron segments including the cortical thick ascending limb of Henle's loop (CAL), the connecting tubule (CNT) and the cortical collecting tubule (CCT) by the in vitro perfusion technique. When PTH (10(-8) mol . l-1) was added to the bath, efflux of Ca2+ (pmol . mm-1 . min-1) was increased from 6.29 +/- 1.46 to 7.96 +/- 1.66 (P less than 0.02) in the CAL, and from 8.55 +/- 1.30 to 13.73 +/- 1.24 (P less than 0.001) in the CNT, respectively, without changes in influx of Ca2+. The effect of PTH on Ca2+ transport in the CAL, however, was abolished when phosphate concentration in the medium was reduced from 3.0 to 1.0 mmol . l-1. When DB-cAMP (10(-3) mol . l-1) was added to the bath, efflux of Ca2+ was also increased from 7.01 +/- 0.83 to 9.40 +/- 0.82 (P less than 0.05) in the CAL, and from 13.11 +/- 0.89 to 19.74 +/- 0.52 (P less than 0.005) in the CNT, respectively. By contrast, neither PTH nor DB-cAMP affected efflux of Ca2+ in the CCT. PTH did not affected the transepithelial voltage either in the CAL or in the CNT. But in the CNT, DB-cAMP decreased the voltage from -14.1 to -9.4 mV. The response of adenylate cyclase activity to PTH in the collagenase treated isolated nephron segments was also examined. Significant increases in adenylase cyclase activity were observed in the CAL as well as in the CNT with 10(-6) mol . l-1 PTH. These data indicate that PTH stimulates Ca2+ transport across the CNT probably via activation of the adenylate cyclase-cyclic AMP system. The hormone may also stimulate Ca2+ transport across the CAL in a special condition where plasma phosphate concentration is elevated.
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PMID:Effects of parathyroid hormone and N6,O2'-dibutyryl cyclic AMP on Ca2+ transport across the rabbit distal nephron segments perfused in vitro. 626 87


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