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)

Amino acid transport was studied in primary cultures of parenchymal cells isolated from adult rat liver by a collagenase perfusion technique and maintained as a monolayer in a serum-free culture medium. Amino acid transport was assayed by measuring the uptake of the nonmetabolizable amino acid, alpha-aminoisobutyric acid. Rat liver parenchymal cells transported alpha-aminoisobutyric acid by an energy-dependent Na+-requiring system which displayed Michaelis-Menten kinetics. Addition of insulin to cultured rat liver parenchymal cells resulted in an increased influx of alpha-aminoisobutyric acid which was reflected in a higher initial rate of alpha-aminoisobutyric acid transport as well as an increased accumulation of alpha-aminoisobutyric acid at later time points. Cycloheximide effectively blocked the increase while results with actinomycin D were equivocal. Insulin at concentrations as low as 50 pM was effective in stimulating alpha-aminoisobutyric acid transport while the maximal response was observed at 80 nM.
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PMID:Induction of amino acid transport in primary cultures of adult rat liver parenchymal cells by insulin. 127 Apr 36

The expression of collagenase and stromelysin is believed to be coordinately regulated. In this report however, we provide evidence that suggests subtle differences may exist in the early events of the induction of these enzymes. Rabbit articular chondrocytes treated with interleukin-1, either alone or in combination with fibroblast growth factor, accumulated steady-state mRNA levels for both the enzymes, with the latter treatment more effective in inducing greater levels and within a shorter time. Further, the induction of the enzymes by either protocol was blocked by cycloheximide co-treatment. Cycloheximide added 1 h post-stimulation with interleukin-1 + fibroblast growth factor failed to block stromelysin mRNA expression, but was able to block collagenase steady-state mRNA levels. Transforming growth factor-beta, another inhibitor of metallprotease induction, showed no such differential activity. The results suggest that collagenase and stromelysin may have subtle variations in their induction pathways. Our studies further show that the enzyme induction by interleukin-1 alone or in combination with fibroblast growth factor occurs through different, but related mechanisms.
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PMID:Differential regulation of metalloprotease steady-state mRNA levels by IL-1 and FGF in rabbit articular chondrocytes. 131 Feb 88

Recombinant human interleukin-1 alpha (IL-1 alpha) induced a time-dependent (0-72 hours) and concentration-dependent (0.01-10 ng/ml) production of metalloproteinases (collagenase, gelatinase, stromelysin) and prostaglandin E2 (PGE2) in rabbit articular chondrocytes (RAC). Exposure of RAC to recombinant human platelet-derived growth factor homodimer BB (PDGF-BB; 2-200 ng/ml) in the presence of stimulatory and substimulatory concentrations of IL-1 alpha resulted in a marked augmentation of metalloproteinase and PGE2 production. PDGF-BB exerted no agonist effects on RAC responsiveness. PDGF-BB up-regulated the number of IL-1 receptors per chondrocyte but had no effect on receptor affinity. Cycloheximide and actinomycin D caused a concentration-dependent suppression of the PDGF-BB-mediated potentiation of radiolabeled IL-1 alpha binding to RAC and cell responsiveness to IL-1 alpha. Similarly, IL-1 increased the number of PDGF receptors on RAC without changing receptor affinity. These data are discussed within the context of cytokine-growth factor interactions as components of the pathogenesis of arthritic diseases.
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PMID:Platelet-derived growth factor potentiates cellular responses of articular chondrocytes to interleukin-1. 205 15

We tested whether aortic endothelial cell (EC)-synthesized substrata, which modulate smooth muscle cell proliferation and EC motility following injury, could influence EC actin cytoskeleton and spreading in vitro. A partial characterization of the substrata indicates that the substratum prepared by deoxycholic acid extraction (DOC-derived substratum) is enriched with fibronectin and type IV collagen. Substratum prepared by removal of the intact monolayer with 20 mM EGTA in PBS (EGTA-derived substratum) contains fibronectin and heparan sulfate proteoglycan, but no type IV collagen. Morphometric analyses were performed on fixed and cytoskeletal antibody treated EC in order to quantitate the extent of spreading and stress fiber (SF) assembly. Compared to plastic, the DOC-derived substratum, a collagenase-treated DOC-derived substratum (CT-DOC-derived substratum) and the EGTA-derived substratum promote EC spreading 2.3-, 2.9- and 1.7-fold, respectively. In addition, there are 4.2-, 4.1- and 2.0-fold more SF on DOC-, CT-DOC- and EGTA-derived substrata, respectively, when compared to plastic. Subcellular fractionation and immunoprecipitation of cytoskeletal proteins from metabolically labeled EC were performed prior to electrophoresis and fluorography. The DOC-derived substratum increases immunoprecipitable actin and myosin 3- to 4.5-fold in both fractions compared to the EGTA-derived substratum and plastic. Collagenase treatment of the DOC-derived substratum partially inhibits this increase. Cycloheximide treatment prevents the rise in soluble actin and myosin as well as causing a reduction in SF number by 1/2 on the DOC-derived substratum and 2/3 on CT-DOC-derived substratum. We propose that fibronectin-collagen interactions are, in part, responsible for inducing endothelial synthesis of cytoskeletal proteins required for SF assembly. This substratum-induced actin-cytoskeletal reorganization facilitates EC spreading in vitro.
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PMID:Substratum-induced stress fiber assembly in vascular endothelial cells during spreading in vitro. 220 Jul 94

Using a collagen film assay utilizing 14C-labeled type I collagen, we demonstrated that cultured human keratinocytes produced a procollagenase after treatment with the tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). Production of collagenase paralleled alterations in cellular morphology induced by TPA. When procollagenase was immunoprecipitated with antibody to human fibroblast collagenase and analyzed on sodium dodecyl sulfate-polyacrylamide gels, the zymogen was revealed as a 56- and 51-kDa doublet. The keratinocyte-derived collagenase was a neutral metalloprotease, required activation with trypsin for detection in the collagenase assay and produced the characteristic three-quarter and one-quarter length collagen cleavage products when incubated with type I collagen at 25 degrees C. The enzyme was inhibited by serum and cysteine and was largely unaffected by serine, thiol, and carboxyl protease inhibitors. Cycloheximide inhibited the TPA-induced production of collagenase, suggesting that the procollagenase was not stored preformed in the keratinocytes. Keratinocytes treated with a tumor-promoting analogue of TPA also produced collagenase, but cells treated with cytochalasin B, interleukin-1, or two non-tumor promoting phorbol esters did not. Keratinocyte-derived collagenase may play a role in wound healing and morphogenesis.
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PMID:Production of procollagenase by cultured human keratinocytes. 243 69

Synoviocytes secrete "chondrocyte activating factors" (CAF) which, like recombinant interleukin-1 (IL-1), induce the synthesis of collagenase by cultures of articular chondrocytes. Enzyme synthesis is preceded by the appearance of collagenase mRNA some 3-5 hours after exposure of the chondrocytes to CAF or IL-1. Cycloheximide (CX) inhibits the appearance of this message in a dose-dependent manner. At a concentration of 5 micrograms/ml inhibition by CX is completely reversible, with superinduction being observed in certain experiments. Identification of the newly synthesised proteins which are required for collagenase mRNA induction would greatly advance our understanding of collagenase gene expression.
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PMID:Cycloheximide inhibits the induction of collagenase mRNA in chondrocytes exposed to synovial factors or recombinant interleukin-1. 255 72

The lipoprotein lipase activity in the liver of neonatal (1 day old) rats was about 3 times that in the liver of adult rats. Perfusion of the neonatal liver with collagenase decreased the tissue-associated activity by 77%. When neonatal-rat liver cells were dispersed, hepatocyte-enriched (fraction I) and haemopoietic-cell-enriched (fraction II) populations were obtained. The lipoprotein lipase activity in fraction I was 7 times that in fraction II. On the basis of those activities and the proportion of both cell types in either fraction, it was estimated that hepatocytes contained most, if not all, the lipoprotein lipase activity detected in collagenase-perfused neonatal-rat livers. From those calculations it was also concluded that haemopoietic cells did not contain lipoprotein lipase activity. When the hepatocyte-enriched cell population was incubated at 25 degrees C for up to 3 h, a slow but progressive release of enzyme activity to the incubation medium was found. However, the total activity (cells + medium) did not significantly change through the incubation period. Cycloheximide produced a time-dependent decrease in the cell-associated activity. Heparin increased the amount of lipoprotein lipase activity released to the medium. Because the cell-associated activity was unchanged, heparin also produced a time-dependent increase in the total activity. In those cells incubated with heparin, cycloheximide did not affect the initial release of lipoprotein lipase activity to the medium, but blocked further release. The cell-associated activity was also decreased by the presence of cycloheximide in those cells. It is concluded that neonatal-rat hepatocytes synthesize active lipoprotein lipase.
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PMID:Lipoprotein lipase activity in neonatal-rat liver cell types. 271 40

The effects of recombinant human tumor necrosis factor alpha (TNF alpha) on collagen production and gene expression in cultured fibroblasts were studied. Cells were labeled with [3H]proline, and the radioactivity of collagenase-sensitive and -resistant proteins were used to calculate the rates of protein production. The net production of collagen relative to total proteins was inhibited by TNF alpha (0-1.2 nM) in a dose- and time-related manner. The specific activities of the free [3H]proline pool, which were similar in control and TNF alpha-treated cells, were used to calculate the absolute rates of protein production. The absolute rate of collagen production was decreased by 50% in the presence of 1.2 nM TNF alpha during 24-h incubations (851 +/- 104 versus 426 +/- 39 pmol/micrograms of DNA/h; p less than 0.01), whereas noncollagen protein production and the rate of procollagen secretion were unchanged. We found no evidence of cellular toxicity in cultured cells treated with TNF alpha. In addition, TNF alpha did not affect cell proliferation as determined by [6-3H]thymidine incorporation into DNA. Most of the collagen produced by the cultured fibroblasts was type I. Using hybridization with specific DNA probes there was an approximately 50% decrease in the quantity of procollagen alpha 1(I) mRNA, without changes in the quantity of alpha tubulin mRNA or the size of the transcripts, in cells incubated with TNF alpha. Interleukin-1 (2.5 ng/ml) also decreased the levels of procollagen alpha 1(I) mRNA by approximately 50%. Cycloheximide (0.1 mM), an inhibitor of protein synthesis, blocked the inhibitory effect of both TNF alpha and interleukin-1 on procollagen alpha 1(I) mRNA. Nuclear run-off assays demonstrated that TNF alpha decreased procollagen alpha 1(I) transcriptional activity by 50% and had no effects on alpha tubulin gene transcription. Thus, TNF alpha decreases collagen gene transcription, collagen mRNA levels, and collagen production in cultured fibroblasts.
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PMID:Tumor necrosis factor alpha inhibits collagen gene transcription and collagen synthesis in cultured human fibroblasts. 325 1

From PMSG-pretreated immature rats, dispersed ovarian cells were prepared with collagenase and DNase and incubated at 37 degrees C in McCoy's 5a medium under 95% air-5% CO2 atmosphere for 4 h. The activities of C17-C20 lyase measured in the 10,000 x g supernatant fluid of the cell homogenates decreased spontaneously with the lapse of time of the incubation. N,N'-Diphenyl-p-phenylenediamine (DPPD, an antioxidant) and actinomycin D inhibited the decrease most effectively. Cycloheximide was also an effective protector. Accordingly, the spontaneous decrease of the lyase activity was caused partly by an oxygen radical-mediated process and partly by a mechanism involving de novo synthesis of RNA and protein. Addition of hCG to the cells further decreased the lyase activity to about half of the control group at 4 h. DPPD itself did not affect the hCG-induced decrease of the lyase activity. However, actinomycin D and cycloheximide prevented the effect of hCG. These results indicate that de novo synthesis of RNA and protein is involved in the latter mechanism, while oxygen radical is not concerned in this process. The decrease of the enzyme activity by hCG during incubation is in agreement with the in vivo effect of hCG upon the lyase activity. On the contrary, at the end of incubation the activity of delta 5-3 beta-hydroxysteroid dehydrogenase (coupled with delta 5-delta 4 isomerase) was more than 89% of that before incubation, and the change of the enzyme activity according to the various treatments was less than 16%.
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PMID:In vitro decrease of lyase activity in rat ovarian cells during incubation: effect of hCG. 345 47

The addition of highly purified elastic fibers to confluent human skin fibroblast or porcine aorta smooth muscle cell cultures resulted in a time-dependent, strong adhesion of the fibrils to the cell surface. The kinetics of adhesion was studied by video/time-lapse cinematography. After a 0.5-1 hr lag period, adhesion progressed to a maximum amount in 3-6 hr in the described conditions. Adhesion is strongly accelerated by the prior addition of soluble elastin peptides (kappa-elastin) to the cultures. Cycloheximide inhibits this induced adhesion. Adherent elastic fibers can be detached by treatment with elastase and trypsin but not with collagenase. The radioactive proteins adhering to elastic fibers, after a 6-hr incubation of the induced cultures in presence of [35S]methionine, were extracted and analyzed by NaDodSO4/PAGE. The proteins strongly adhering to the elastic fibers had apparent molecular sizes of about 120, 67, 60, and 45 kDa. Only the 120-kDa protein band showed a significant increase of its associated radioactivity in the induced cultures as compared to the noninduced cultures. We propose that the 120-kDa protein is responsible for the induced adhesion of mesenchymal cells to elastic fibers and designate it "elastonectin."
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PMID:Inducible adhesion of mesenchymal cells to elastic fibers: elastonectin. 346 47


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