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:4.2.2.7 (heparinase)
1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The changes in levels of glycosaminoglycans (GAGs) of the intima and media of the human artery in atherosclerosis were determined by a recently introduced two-dimensional electrophoresis technique that permits direct measurments of each of these macromolecules. To identify the arterial GAGs, they were fractionated by chromatography on a DEAE-Sephadex A-25 column, and the resulting three fractions (hyaluronic acid [HA], heparan sulfate [HS], and the partially separated chondroitin sulfates B [CSB] and C [CSC]) were analyzed for their electrophoretic mobilities by this electrophoretic method, for their digestability by highly specific hydrolases (leech hyaluronidase, heparinase, and chondroitinases ABC and AC) and for their iduronic acid content. From these studies we concluded that normal and atherosclerotic human aortas contain CSB, CSC, HA, and HS. Further, we demonstrated that CSB is a hybrid consisting of approximately 40% CSA and 60% CSB and that CSC appears to be a polymer consisting essentially of glucuronic acid and N-acetylgalactosamine-6-sulfate. Classical CSA as well as chondroitin (CH) were not present in detectable amounts. In the relatively normal intima, the mean concentrations of the GAGs were found to be 4.7, 20.9, 1.3, and 5.1 mg/g of dry, defatted, decalcified tissue for CSB, CSC, HA, and HS, respectively. With the progression of atherosclerosis, there was a pronounced decrease in the total GAG content (from 32 to 18 mg) associated with a decrease in the CSC and HS levels but without a change in the HA concentrations. Of particular interest, however, was the increase in the CSB level. In the media whose total GAG content averaged approximately 20 mg, no significant changes in these GAG levels were noted with the progression of the disease except for that of CSC. These findings may be important in explaining the increased lipoprotein and collagen deposition in the diseased aorta.
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PMID:The glycosaminoglycans of the human artery and their changes in atherosclerosis. 13 44

The study of factors affecting phenotypic change and growth of aortic smooth muscle cells (SMC) typically involves either the isolation of SMC by enzymatic dissociation or observation of outgrowth of cells from primary explants of vascular tissue. Explants provide a system in which the growth of cells can be investigated without dissociating them totally from their normal environment and avoids some of the problems of variability associated with enzymatic digestion. We describe here a standardised method for the preparation of medial explants of arterial tissue using a McIlwain tissue chopper, which is both fast and reproducible. Measurement was made of the percentage of explants showing outgrowth and of the distance migrated by cells at various times after plating explants singly into wells of a 96-well plate. Using this method, by 12 days after explanting, more than 95% of explants from normal rabbit aorta had shown outgrowth, in contrast to only 50% of explants prepared using a scalpel blade. Explants from atherosclerotic rabbit aorta showed a shorter lag phase before outgrowth commenced than explants from normal rabbit aorta of a similar age, but the subsequent rate of growth was the same. In contrast, when explants of normal rabbit aorta were grown in hyperlipidic rabbit serum, the lag phase was the same as for normal serum, but the subsequent rate of growth was greater. Explants from normal rabbit aorta treated with heparin showed an increased lag phase but reduced rate of growth. Treatment with heparinase decreased the lag phase and increased the rate of growth as did elastase.
Atherosclerosis 1991 Feb
PMID:A standardised method of culturing aortic explants, suitable for the study of factors affecting the phenotypic modulation, migration and proliferation of aortic smooth muscle cells. 187 16

We have studied the ability of particulate stimuli to induce the release of reactive oxygen metabolites from sub-cultured monolayers of human endothelial cells. Basal release of superoxide (O2-) and hydrogen peroxide from undisturbed monolayers was very low (108 pmol O2- and 75 pmol H2O2 in 3 h from dishes of 3 X 10(5) cells). Addition of 1-micron diameter polystyrene microspheres, which were phagocytosed by the cells progressively, caused a dramatic increase in release of both metabolites; by 3 h, a 13.5- and 6.6-fold increase over controls was observed respectively (P less than 0.001). Addition of formaldehyde-fixed human platelets or chylomicron-size lipid particles also increased production of reactive oxygen species. Similar rises in H2O2 and O2- production were induced by treatment with 10(-7) M phorbol myristate acetate. Pretreatment of endothelial cells with neuraminidase, heparinase or heparitinase to alter their glycocalyx composition substantially enhanced the effect of microspheres on H2O2 and O2- generation. We conclude that the interactions of particles, including platelets and lipids, with endothelial cells leads to the generation of significant pericellular levels of reactive oxygen species. These metabolites can oxidise a wide variety of nearby molecules, leading to cell damage and altered uptake characteristics for lipoproteins containing peroxidized lipids. These effects are exacerbated when endothelial cell glycocalyx composition is disrupted.
Atherosclerosis 1988 Jul
PMID:Generation of reactive oxygen metabolites by phagocytosing endothelial cells. 285 Aug 6

Oligosaccharide fragments of heparin were prepared using flavobacterial heparinase. Following sizing, these oligosaccharide fractions were administered (i.v.) to rabbits and were examined for their ability to release lipoprotein lipase. The decasaccharides (dp = 10, Mr avg = 2,800) were the smallest oligosaccharides which resulted in substantial lipase release. The plasma lipase levels obtained with decasaccharides were comparable to low molecular weight heparin and one-third those obtained when heparin was administered at an equivalent dose. The peak plasma lipase concentration was observed 10 min following heparinization and fell off rapidly over the 60-min time course. The lipase release activity paralleled the in vivo pharmacokinetics of the heparin and decasaccharide sample as determined by monitoring their anti-Factor Xa activity. No activation of purified bovine milk lipoprotein lipase or plasma lipase was detectable at the concentrations studied, indicating that the increase in circulating lipolytic activity was due entirely to release. Lipoprotein lipase accounted for a major portion of the released activity with hepatic triglyceride lipase representing the remainder of the lipolytic activity. The sized decasaccharide sample was characterized with regards to its structure and anticoagulant activity. The decasaccharides exhibited reduced anticoagulant activity possibly making it a better drug candidate in the treatment of atherosclerosis.
Atherosclerosis 1986 Nov
PMID:Effect of very low molecular weight heparin-derived oligosaccharides on lipoprotein lipase release in rabbits. 380 Oct 83

Heparin and heparan sulfate proteoglycans (HSPGs) stabilize FGFs which belong to heparin-binding growth factors (HBGFs) on active conformation. They also strongly potentiate their mitogenic activity on many cell types, and protect them against thermal denaturation and enzymatic degradation. In the present work we have tested two heparin-like substances named mesoglycan and sulodexide obtained from bovine intestinal mucosal extracts. These products are used as heparin, in various of therapeutic fields such as atherosclerosis or antithrombotic therapy. The compositions of mesoglycan and sulodexide are partially known and include chondroitin, dermatan and heparan sulfate. We have shown that mesoglycan and sulodexide potentiated the mitogenic activity of FGF1 and FGF2. The magnitude of this effect was identical with that of heparin used as a control substance but at double concentration. Mesoglycan and sulodexide also exerted stabilizing and protective effects on FGFs for heat denaturation and enzymatic degradation. The suppression of the protective properties after heparinase treatment of mesoglycan and sulodexide indirectly demonstrated the presence of heparan sulfate which was shown to represent about 60% of the commercial products.
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PMID:Mesoglycan and sulodexide act as stabilizers and protectors of fibroblast growth factors (FGFs). 754 22

Lipoprotein lipase (LPL) is rapidly and efficiently cleared from the circulation by the liver through an as yet unclear mechanism. In the present study, we determined the nature of LPL interactions with the liver parenchimal cell line HepG2 as compared to other cells in culture. Binding, cell association and degradation of 125I-labelled bovine milk LPL by HepG2 cells, normal and low density lipoprotein (LDL) receptor-negative human fibroblasts and Chinese hamster ovary (CHO) cells show similar values irrespective of source and origin. LPL metabolism in HepG2 cells was characterized by a high capacity to degrade the enzyme, an extremely high sensitivity to heparin and was inhibited by 60%-70% after treatment of the cells with sodium chlorate and heparinase (but not chondroitinase). These findings suggested an important role for heparan sulfate in the process of cell interaction and metabolism of LPL. To further clarify the role of heparan sulfate in determining the LPL-cell interactions, we compared the metabolism of LPL in wild type and mutant heparan sulfate-deficient CHO cells. Heparan sulfate-deficient CHO cells show a low capacity to bind and degrade LPL, about 10%-20% that of the wild type cells. In another set of experiments, we sought to determine whether LPL interactions with HepG2 cells are affected by triglyceride-rich lipoproteins. The results clearly show that whereas unlabeled LPL dramatically enhanced the metabolism of radioiodinated very low density lipoprotein (VLDL), unlabeled VLDL had no effect on radioiodinated LPL metabolism in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Atherosclerosis 1995 Apr 07
PMID:Binding to heparan sulfate is a major event during catabolism of lipoprotein lipase by HepG2 and other cell cultures. 760 68

Matrix production by smooth muscle cells (SMC) appears to play a major role in the intimal thickening process. Proteoglycans (PG) are the predominant extracellular matrix component of early restenotic lesions. As angiotensin II (A II) has been proposed as a mediator of restenotic process, we hypothesized that A II may directly affect PG synthesis by SMC. SMC were cultured in the presence of [35S]sulfate and angiotensin II, and both the secreted and membrane-bound proteoglycans were analyzed. A II (1 to 100 nM) evoked a dose- and time-dependent increase in both cell- and media-associated PG production, an effect abrogated by the A II receptor antagonist, saralasin. SMC constitutively synthesize small amounts of PG with a molecular mass of 170-250 kDa. After treatment with A II, the abundance of PG is increased, as well as its molecular mass (230-300 kDa). Selective degradation by chondroitinases and heparinase identified chondroitin and dermatan sulfate PG as the predominant form being induced. These results demonstrate that the effect of A II is not general and is specific to certain classes of PGs. In order to further examine the specificity of the A II effect, we compared the synthesis of PG induced by A II with that induced by platelet-derived growth factors AA and BB (PDGF-AA and -BB), insulin-like growth factor I (IGF-I), and tumor necrosis factor alpha (TNF alpha). This comparison demonstrated that the profile of PG induced by A II is different from the other factors examined. Taken together, these data indicate that A II may not only function as a hypertrophic factor for SMC, but in addition may also be a potent modulator of specific PG synthesis by these same cells, which could significantly contribute to the formation of atherosclerotic and restenotic lesions.
Atherosclerosis 1994 Nov
PMID:Stimulation of rat vascular smooth muscle cell glycosaminoglycan production by angiotensin II. 784 Aug 14

Embryonic data and ultrastructural analyses suggest that the primitive endothelium signals undifferentiated mesenchymal cells to migrate to the forming blood vessel and subsequently regulates mural cell growth and behavior. Upon maturation of the blood vessel, chemotactic and mitogenic signals are apparently diminished and differentiated smooth muscle cells normally remain quiescent. This homeostasis is seemingly upset in conditions which lead to pathologies characterized by smooth muscle cell hyperplasia such as atherosclerosis. By culturing endothelial cells at different densities, we attempted to re-create the various stages of vascular development. Whereas media conditioned by sparse endothelial cells stimulate smooth muscle cells, media conditioned by dense endothelial cell cultures are inhibitory. Culture of sparse smooth muscle cells in media conditioned for 3 days by postconfluent endothelial cell cultures leads to dose-dependent and reversible smooth muscle cell inhibition. Furthermore, in the presence of the endothelial cell-derived inhibitor, smooth muscle cells are rendered refractory to mitogens such as fibroblast growth factor and platelet-derived growth factor. The inhibitory activity is not attributable to the well-characterized inhibitors of smooth muscle cell growth, transforming growth factor type-beta, prostaglandin I2, or heparan sulfate proteoglycan. Partial characterization of the inhibitory conditioned media suggests that the active molecule is smaller than 1,000 da, and stable to boiling as well as proteinase K and heparinase digestion. These findings support the concept that there is intercellular communication between endothelial cells and smooth muscle cells and provide evidence for a novel endothelial cell-derived smooth muscle cell growth inhibitor.
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PMID:Density-dependent endothelial cell production of an inhibitor of smooth muscle cell growth. 822 80

Plasma phospholipid binding to cell-derived cholesterol is important in reverse cholesterol transport, a key step in the regression of atherosclerosis. However, the mechanism by which phospholipids are transferred from cells to plasma remains unclear. [3H]Choline-labeled phospholipid efflux from fibroblasts has been studied using plasma and its components as acceptors. The kinetics were resolved into a fast component (k1 = 0.119 +/- 0.23 min-1) that corresponded to high-affinity binding of high-density lipoproteins (HDL) to the cell surface and a slow component (k2 = 0.0047 +/- 0.0009 min-1) due to protein-mediated desorption (n = 3). Altering the donor charge with heparinase or the acceptor charge by acetylation abolished the fast component, while the slow phase was unchanged. Only HDL displayed biexponential kinetics, comparable to whole plasma. Half-lives for low-density lipoprotein and very-low-density lipoprotein were t1/2 = 278 +/- 22 min and t1/2 = 1003 +/- 147 min, respectively. In the absence of transfer factor, HDL alone significantly reduced phospholipid efflux (t1/2 = 663 min). Phospholipid transfer protein restored biexponential kinetics. We conclude that cell membranes are a potentially important source of plasma phospholipids and that protein-mediated transfer to HDL is the major route for cell-to-plasma transfer. This step represents a locus for anti-atherosclerotic intervention.
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PMID:Mechanism of cellular phospholipid efflux. 823 Nov 74

The cause and consequence of altered proteoglycans in atherosclerosis are poorly understood. To determine whether proteoglycans affect monocyte binding, we studied the effects of heparin and proteoglycan degrading enzymes on THP-1 monocyte adhesion to subendothelial matrix (SEM). Monocyte binding increased about 2-fold after SEM was treated with heparinase. In addition, heparin decreased monocyte binding to fibronectin, a known SEM protein, by 60%. These data suggest that SEM heparan sulfate inhibits monocyte binding to SEM proteins. We next examined whether lysolecithin, a constituent of modified lipoproteins, affects endothelial heparan sulfate proteoglycan (HSPG) production and monocyte binding. Lysolecithin (10-200 microM) decreased total 35SO4 in SEM (20-75%). 2-fold more monocytes bound to SEM from lysolecithin treated cells than to control SEM. Heparinase treatment did not further increase monocyte binding to lysolecithin-treated SEM. HSPG degrading activity was found in medium from lysolecithin-treated but not control cells. 35SO4-labeled products obtained from labeled matrix treated with lysolecithin-conditioned medium were similar in size to those generated by heparinase. These data suggest that lysolecithin-treated endothelial cells secrete a heparanase-like activity. We hypothesize that decreased vessel wall HSPG, as occurs in atherogenic conditions, allows increased monocyte retention within the vessel and is due to the actions of an endothelial heparanase.
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PMID:Lysolecithin-induced alteration of subendothelial heparan sulfate proteoglycans increases monocyte binding to matrix. 853 Mar 67


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