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 previously shown that bone cells possess glucocorticoid receptors and that, in addition to being inhibitory to cell growth, glucocorticoid treatment potentiates the ability of parathyroid hormone (PTH) to stimulate cyclic AMP (cAMP) formation. This study extends those observations to specific subpopulations of bone cells and explores the mechanism of the cAMP augmentation. Subpopulations of cultured bone cells derived from 20-d-old fetal rat calvaria were enriched for "osteoblast-like" (OB) and "osteoclast-like" (OC) cells by sequential collagenase digestion. OC cells released during the first 30 min of collagenase digestion were characterized by low alkaline phosphatase activity, a cAMP response to salmon calcitonin (CT), but only a small cAMP response to bovine PTH. In contrast, OB cells released between 30 and 120 min of collagenase digestion, possessed high alkaline phosphatase activity, responded with a large cAMP rise to PTH, but exhibited no response to CT. Glucocorticoid receptors, with similar properties, were demonstrated in both populations (K(d) congruent with 5 nM, N(maximum) congruent with 400 fmol/mg cytosol protein). Dexamethasone equivalently inhibited cell growth and alkaline phosphatase activity in both populations. Dexamethasone potentiation of cAMP generation occurred after PTH but not CT stimulation. A greater enhancement of cAMP generation observed in OB cells appears to result from two glucocorticoid actions: (a) stimulation of adenylate cyclase and (b) inhibition of phosphodiesterase. Only the latter mechanism was found in OC cells. Dexamethasone-treated cells showed an increase in both sensitivity and maximal response of cAMP to PTH. The possible relationship of these actions to the mechanism of glucocorticoid-induced osteopenia is discussed.
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PMID:Glucocorticoid receptors and actions in subpopulations of cultured rat bone cells. Mechanism of dexamethasone potentiation of parathyroid hormone-stimulated cyclic AMP production. 22 Feb 82

We have previously identified glucocorticoid binding proteins in cytosol of cells dispersed from fetal rat calvaria by collagenase digestion. The present study, employing primary culture of these cells, provides further evidence that these binding proteins represent glucocorticoid receptors. [3H]Dexamethasone bound to cytoplasmic extracts of cultured cells with an apparent Kdiss of 6.8 nM and exhibited approximately 8500 binding sites/cell. Nuclear translocation of [3H]dexamethasone was demonstrated with approximately 50% of bound steroid extractable from the nuclear pellet after incubation at 37 C; little nuclear transfer occurred at 0 C. The specificity of these binding site was characterized by competition studies with other steroids in whole cells, the order of affinities being: triamcinolone acetonide greater than dexamethasone greater than progesterone greater than cortisol greater than corticosterone = cortexolone. Non-glucocorticoids except progesterone competed only poorly. Sedimentation analysis of [3H]dexamethasone-protein complexes on sucrose gradients revealed a cytoplasmic peak of 6.5 S in salt-free gradients and 3.8 S in 0.3 M KCl gradients. Dexamethasone addition to the culture medium resulted in a dose-dependent inhibition of cell growth with approximately 40% reduction in cell number at 13 nM. That this inhibition was receptor mediated was substantiated by the partial blockade of the dexamethasone effect in the presence 1.3 microM progesterone. Functionally, dexamethasone inhibits the growth of these cells. These data provide evidence for receptor mediated inhibitory effects of glucocorticoids directly at the level of the bone cell.
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PMID:Glucocorticoid receptors and inhibition of bone cell growth in primary culture. 40 Oct 16

Parenchymal cells from adult rat liver, isolated by a collagenase perfusion technique, have been maintained in primary culture and a detailed study on carbohydrate metabolism carried out over the initial 48-hour culture period. The glucose concentration of the medium exerts a major influence on glycogen accumulation by the cells. Insulin, particularly at high glucose concentrations, stimulates glycogen biosynthesis, whereas glucagon prevents glycogen accumulation. Dexamethasone was without effect on glycogen metabolism. Glucose appears to stimulate glycogen accumulation by activation of glycogen synthetase enzyme. However, there is a gradual loss of synthetase activity throughout the culture period. Similar decreases in activity were noted for pyruvate kinase, aldolase and hexokinase. Glucose, insulin and dexamethasone were unable to prevent these decreases in enzyme activity. Foetal bovine serum contains fructose and this hexose appears to be the factor in serum which is responsible for the activation of glycogen accumulation in the presence of physiological glucose concentrations. The lactic acid content of the serum may also stimulate glycogen accumulation. In general, there is a gradual loss of the pattern of carbohydrate metabolism typical of differentiated hepatocytes during the culture period.
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PMID:Effects of hormones and serum on glycogen metabolism in adult rat liver parenchymal cell primary cultures. 40 98

Although adipose tissue appears to be a target organ for glucocorticoid hormones, previous studies have failed to detect glucocorticoid receptors in this tissue. In the present study, the addition of thioglycerol and trasylol to the homogenization medium provided an enuironment in which receptors were successfully demonstrated. [3H]Dexamethasone binding studies were carried out at 0 C in cytosol from various adipose tissues of adrenalectomized rats and bound hormone was separated from free by Sephadex chromtography. Despite the presence of protein protective agents, receptor binding decayed significantly over 24 h but appeared stable from 1 to 5 h. Epididymal fat pad cytosol had an apparent Kdiss at 0 C for dexamethasone of approximately 6 nM and a binding capacity of approximately 200 fmol per mg protein. To prove that the receptors were located in fat cells and not in surrounding connective tissue, isolated adipocytes were prepared by collagenase digestion and receptors were demonstrable in the cytosol from these cells as well. The affinity of series of steroids for the receptor was in the sequence: dexamethasone greater than corticosterone greater than progesterone greater than aldosterone greater than cortexolone greater than testosterone greater than estradiol. Receptors of roughly the same affinity but somewhat fewer binding sites on the basis of cytosol protein were also found on other fat depots including peri-renal, peri-scrotal and popliteal. Of interest is the fact that interscapular brown fat and human subcutaneous fat also possessed similar these receptors, the higher competitive capacity of dexamethasone indicated that the binding was to glucorticoid rather than mineralocorticoid receptors. The data suggest that fat cells contain glucocorticoid receptors which are similar to those seen in other glucocorticoid targets. Presumably these receptors mediate the effects of glucorticoids on adipose tissue.
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PMID:Glucocorticoid receptors in adipose tissue. 83 31

The described model of experimental pneumocystosis is based on the induction of natural latent infection of P. carinii in Wistar strain laboratory rats. As to pharmacological inducing agents immunosuppresive preparations such as Hydrocortisone sol. inj. (Spofa), Cyclosporin A (Merck) and Dexamethasone (Spofa) were used whereby the latter was effective in up 50%. As to non-pharmacological inducing agents, the authors used in combination with the tested inducers a low protein diet (less than 8% protein in the diet); for suppression of associated bacterial contamination tetracycline was added to drinking water. From the infected lungs by two different methods two types of antigens were prepared 1) PCL antigen (Pneumocystis carinii lavage antigen) isolated by rinsing of the lungs and 2) PCWD antigen (P. carinii whole digest antigen) isolated by digestion of the lungs with collagenase and trypsin. Cysts of P. carinii were detected by staining according to Giemsa (staining of internal structures of nuclear cysts) and by modified staining with toluidine blue O (staining of the cyst wall). For isolation of the antigen and for detection of cysts a combination of the two described methods seems to be best.
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PMID:[Induction of experimental pneumocystosis, detection and primary isolation of Pneumocystis carinii]. 182 70

A number of peptide growth factors have been shown to induce the secretion of type I collagenase into the medium of human fibroblast cultures (Chua et al., 1985). In this study the ability of eye-derived growth factor, lectin and tumor-promoting agents on collagenase induction in human fibroblast cells were examined. These agents were found to be able to induce collagenase production to a similar extent as epidermal growth factor. Dexamethasone at 10-100 nM was found to suppress collagenase induction in human fibroblast cells. The cell-type specificity of this enzyme induction by growth factors was studied by using a human epidermoid carcinoma cell line, A-431. An Mr 55,000 band appeared in the medium of A-431 cells upon 22 h exposure to EGF. Two-dimensional peptide pattern of the Mr 55,000 band in A-431 cells was identical to the counterpart in HF cells. Our results indicated that the induction of collagenase was not unique to human fibroblast cultures.
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PMID:Induction and suppression of type I collagenase in cultured human cells. 282 42

The regulation of the expression of interstitial collagenase and tissue inhibitor of metalloproteinases (TIMP) was examined in response to both retinoid compounds and glucocorticoids. Effective retinoids induced a dose-dependent, specific increase in the production of TIMP of approximately two- to threefold by monolayer cultures of human fibroblasts derived from various tissues, while simultaneously causing a decrease in collagenase secretion of similar magnitude. These effects were apparent by 8-12 h in culture and disappeared within 24 h after the withdrawal of retinoid compounds. The retinoid effect on TIMP production was mediated via an increased biosynthesis of new inhibitor protein. Similarly, increased steady state levels of TIMP messenger RNA (mRNA) accompanied by decreased quantities of collagenase mRNA were demonstrated, suggesting transcriptional control of the retinoid action. The data suggest that retinoids co-regulate the expression of collagenase and TIMP, and do so in an inverse manner. Dexamethasone caused a dose-dependent, specific decrease in collagenase production without altering the biosynthesis of TIMP. These findings were paralleled by a marked reduction in collagenase mRNA, without any accompanying change in TIMP mRNA. Therefore, TIMP and collagenase expression appear to be independently modulated by glucocorticoids.
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PMID:Regulation of the expression of tissue inhibitor of metalloproteinases and collagenase by retinoids and glucocorticoids in human fibroblasts. 282 58

Glucocorticoids inhibit collagenase accumulation in the medium of human skin explant cultures. To examine the mechanism for this process, skin fibroblasts were placed in serum-free medium containing various steroids. Dexamethasone produced a dose-dependent inhibition of trypsin-activatable collagenase in the culture medium with maximal inhibition of approx. 85% at 10(-6) M. Dexamethasone failed to inhibit collagenase activity directly. The decrease in activity in the medium was paralleled by a decrease in immunoreactive protein, suggesting inhibition of enzyme synthesis. The specificity of the effect was shown in two ways. At 10(-6) M steroid, only dexamethasone and hydrocortisone were inhibitory; estradiol, progesterone and testosterone produced less than 10% inhibition. In biosynthetic studies, exposure to 10(-7) M dexamethasone for 24 h produced approx. 50% inhibition of collagenase synthesis but caused no greater than 10% inhibition of total protein synthesis. The T1/2 for achieving the effect was approx. 16 h after initial exposure to dexamethasone. These kinetics were parallel to the inhibition caused by actinomycin D and cordycepin, two inhibitors of transcription, but were longer than that caused by cycloheximide (T 1/2 less than 3 h). To examine this process, cells were cultured in the presence or absence of 10(-6) M dexamethasone prior to harvesting mRNA for cell-free translation. In each case the inhibition or enzyme activity in the intact cells was paralleled by a reduction in translatable collagenase mRNA from the same cells. At the same time, there was no significant inhibition of total protein translation by the steroid. These data suggest that glucocorticoids regulate collagenase synthesis at a pre-translational level, possibly through inhibition of transcription.
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PMID:Glucocorticoid modulation of collagenase expression in human skin fibroblast cultures. Evidence for pre-translational inhibition. 298 28

Macrophages, which produce the collagenolytic enzyme collagenase, are commonly found at sites of connective tissue destruction in chronic inflammatory lesions. Since tissue macrophages are derived from circulating peripheral blood monocytes, we used these less-differentiated, more readily available cells to examine the production and regulation of collagenase. Human monocytes, isolated in large quantities by counterflow centrifugal elutriation, were shown to produce substantial amounts of collagenase when stimulated by concanavalin A (Con A) and to a lesser extent with lipopolysaccharide, while unstimulated monocyte cultures produced negligible collagenase. Collagenase was detected in the culture media within the first 24 hr of culture after activation with peak production at 48 hr. Analysis of the intracellular regulation of collagenase revealed that synthesis of this enzyme required a prostaglandin (PGE2)-dependent step since indomethacin-inhibited enzyme synthesis was reversed by PGE2. Additionally, dibutyryladenosine cyclic monophosphate (dBcAMP) restored collagenase synthesis in indomethacin-blocked cultures, indicating a PGE2-dependent generation of cAMP requirement for collagenase production similar to that demonstrated in experimental animals systems. In additional studies, anti-inflammatory drugs which are known to modulate connective tissue destruction were analyzed for their influence on monocyte-derived collagenase. Dexamethasone, colchicine or retinoic acid all inhibited collagenase synthesis by monocytes in a dose-dependent manner although the effect of these drugs on monocyte PGE2 synthesis differed. Dexamethasone inhibited PGE2 synthesis, which resulted in the suppression of collagenase. However, PGE2 production was unaffected by colchicine whereas retinoic acid caused a significant increase in PGE2 levels. Inhibition of collagenase synthesis by dexamethasone, but not colchicine or retinoic acid, could be reversed by PGE2 or phospholipase A2. These findings provide insight into the intracellular events regulating monocyte collagenase synthesis and also implicate monocytes as a target of anti-inflammatory agents which ameliorate connective tissue degradation associated with chronic inflammatory lesions.
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PMID:Regulation of human peripheral blood monocyte collagenase by prostaglandins and anti-inflammatory drugs. 303 63

The effect of dexamethasone on the synthesis and degradation of type IV collagen was studied in human fibrosarcoma cells, HT-1080. A dexamethasone concentration as low as 0.1 microM markedly increased collagen synthesis in HT-1080 cells labelled with [14C]proline. The increase in type IV collagen synthesis was not specific, since total protein synthesis was also increased. Further studies indicated that part of the increase was due to an increase in the specific radioactivity of the intracellular proline pool, after dexamethasone treatment. In fact, with dexamethasone concentrations of 0.1-10 microM the relative collagen synthesis was decreased, indicating that synthesis of other protein was increased more than that of type IV collagen. This was also confirmed by measuring the relative amount of type IV collagen RNA by using recombinant plasmid cDNA specific for the human procollagen pro alpha l (IV) RNA. The results indicated that relative collagen synthesis and the relative amount of type IV collagen messenger RNA was decreased similarly, indicating that dexamethasone affected type IV collagen synthesis at the pre-translational level. The dexamethasone-induced effect on total protein and collagen synthesis was maximal after 12-24 h. Dexamethasone induced a marked accumulation of collagen into the cell layer, leading to diminished deposition of soluble collagen into the medium. Since bacterial-collagenase treatment of the cell layer drastically decreased the collagen content of the dexamethasone-treated cells, this indicates that dexamethasone caused an accumulation of collagen into the extracellular matrix of the cell layer. In contrast, the amount of fibronectin was markedly increased in the medium. Dexamethasone decreased the type IV collagen-degrading activity in HT-1080 cells. The HT-1080 cells contained glucocorticoid receptors, as demonstrated by two different methods: by a whole-cell binding assay and by using a cytosol-gel-filtration method. The number of specific binding sites was similar to that in human skin fibroblasts. In conclusion, glucocorticoids affect the metabolism of type IV collagen and fibronectin in HT-1080 cells, and, since these cells contain specific glucocorticoid receptors, the effects are apparently receptor-mediated.
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PMID:Dexamethasone modulates the metabolism of type IV collagen and fibronectin in human basement-membrane-forming fibrosarcoma (HT-1080) cells. 366 50


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