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)

Previously we reported that, in vitro, lens cells proliferate, migrate or differentiate in response to low, medium and high concentrations of FGF respectively. To examine further the role of FGF in lens development we used immunohistochemistry to study the distribution of aFGF and bFGF in the eye of the 20 day rat foetus. Strong aFGF-like reactivity was localised in a band of cells near the lens equator which included the germinative zone where most cell proliferation occurs and the transitional zone where epithelial cells differentiate into fibres. The closely apposed inner epithelial layer of the ciliary and iridial retina also reacted strongly. Reactivity for aFGF was also found in the epidermis and in the corneal and conjunctival epithelia. In the neural retina, reactivity was found in the nerve fibre layer and in isolated cells of the inner plexiform layer. bFGF-like reactivity was found in the retinal ganglion cell layer, extra-ocular muscles and associated with endothelial cells of the hyaloid, lenticular and choroid vasculatures. Pre-digestion of sections with hyaluronidase caused loss of cell-associated reactivity but revealed strong bFGF-like reactivity in ocular basement membranes, in particular, the lens capsule. The sensitivity of this capsular bFGF localisation to heparinase indicates that bFGF in the extracellular matrix is complexed with heparan sulphate proteoglycans. The results of this study are consistent with the hypothesis that FGF plays an important role in lens development via both autocrine and paracrine mechanisms.
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PMID:Distribution of acidic and basic fibroblast growth factors (FGF) in the foetal rat eye: implications for lens development. 137 41

Cultured bovine capillary endothelial (BCE) cells synthesize heparan sulfate proteoglycans (HSPG), which are both secreted into the culture medium and deposited in the cell layer. The nonsoluble HSPGs can be isolated as two predominant species: a larger 800-kD HSPG, which is recovered from preparations of extracellular matrix, and a 250-kD HSPG, which is solubilized by nonionic detergent extraction of the cells. Both HSPG species bind bFGF. 125I-bFGF bound to BCE cell cultures is readily released by either heparinase or plasmin. When released by plasmin, the growth factor is recovered from the incubation medium as a complex with the partly degraded high molecular mass HSPG. Endogenous bFGF activity is released by a proteolytic treatment of cultured BCE cells. The bFGF-binding HSPGs are also released when cultures are incubated with the inactive proenzyme plasminogen. Under such experimental conditions, the release of the extracellular proteoglycans can be enhanced by treating the cells either with bFGF, which increases the plasminogen activating activity expressed by the cells, or decreased by treating the cells with transforming growth factor beta, which decreases the plasminogen activating activity of the cells. Specific immune antibodies raised against bovine urokinase also block the release of HSPG from BCE cell cultures. We propose that this plasminogen activator-mediated proteolysis provides a mechanism for the release of biologically active bFGF-HSPG complexes from the extracellular matrix and that bFGF release can be regulated by the balance between factors affecting the pericellular proteolytic activity.
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PMID:Release of basic fibroblast growth factor-heparan sulfate complexes from endothelial cells by plasminogen activator-mediated proteolytic activity. 213 29

The binding of [125I]-recombinant basic FGF (rec bFGF) to rat hepatic plasma membranes was investigated. [125I] rec bFGF bound to an apparent single class of high affinity binding sites (KD = 69 pM; Bmax = 9.61 fmoles/mg proteins). The absence of low affinity sites was confirmed by the inability of sulphated polysaccharides and heparinase to interfere with FGF binding. A good correlation existed between the ability of bovine pituitary-derived bFGF, rec bFGF and bovine brain-derived aFGF to displace [125I]rec bFGF from these binding sites and their in vitro potency on bovine aortic endothelial cell proliferation.
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PMID:High affinity binding sites for basic fibroblast growth factor in rat hepatic plasma membranes. 256 19

Heparan sulfate (HS) secreted into the medium of bovine aortic endothelial cell (BAEC) cultures was subjected to chemical and enzymatic degradation followed by analysis using gel-filtration and ion-exchange chromatography. Treatment with HNO2 showed that 41% of the disaccharides were N-sulfated. Degradation by Heparin lyases I (Hep I) showed that 8-9% of the disaccharides contained IdoA(2S) residues. Heparin lyase III (Hep III) degradation produced mainly disaccharides with 67% of the molecules glycosidic linkages susceptible to cleavage. Further degradation of Hep III-resistant fragments with Hep I showed that IdoA(2S) residues were predominantly positioned centrally within the repeating GlcNSO3(+/- 6S)alpha 1-4IdoA containing domains. Digestion with a mixture of Heparin lyases I, II and III degraded the molecule almost entirely to disaccharides, with small amounts of tetrasaccharides containing resistant linkages, suggesting the presence of 3-O sulfated GlcNSO3. Further analysis of the disaccharide products by ion-exchange chromatography and comparison with the data from single enzymatic digestion, allowed an estimate of the disaccharide composition to be made. The results suggest an ordered arrangement of structural domains; however, variations in the structure of these domains results in a heterogeneous population of HS chains. It is suggested that biosynthetic differences in HS structure may act as a regulator of bFGF induced cellular responses.
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PMID:Molecular attributes of bovine aortic endothelial cell heparan sulfate. 776 9

Homosexual males often present signs of immune activation and are likely to have increased levels of inflammatory cytokines such as IL-1 beta, TNF-alpha, and IFN-gamma. These individuals develop Kaposi's sarcoma (AIDS-KS) more frequently than other HIV-1-infected groups. Our previous work demonstrated that inflammatory cytokines stimulate the growth of spindle cells derived from AIDS-KS lesions (AIDS-KS cells) and that these cells produce high levels of bFGF that mediate autocrine and paracrine (endothelial) cell growth and angiogenesis. Here we show that AIDS-KS cells constitutively produce and release bioactive bFGF in the absence of cell death, and that extracellular bFGF exist in both a soluble and a bound form; the latter can be released by treatment with trypsin, heparin, or heparinase I. Inflammatory cytokines stimulate both the synthesis and release of biologically active bFGF from KS cells and enhance their ability to induce angiogenic KS-like lesions in nude mice. Because bFGF is highly expressed in primary KS lesions, and is a mediator of KS-like lesion formation, these results suggest that the export of bFGF induced by inflammatory cytokines may play a critical role in the induction and progression of KS in HIV-1-infected homosexual men.
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PMID:Inflammatory cytokines induce AIDS-Kaposi's sarcoma-derived spindle cells to produce and release basic fibroblast growth factor and enhance Kaposi's sarcoma-like lesion formation in nude mice. 789 37

Previous studies have shown that basic fibroblast growth (bFGF) has a biphasic effect on 125I-hCG binding to LH receptors in cultured Leydig cells from immature rats. Low concentrations of bFGF (0.1-1.0 ng/ml) progressively decreased binding, while higher concentrations (10-100 ng/ml) progressively increased binding above nadir levels. In the present studies, treatment of cultured immature Leydig cells with heparinase I and/or heparinase III, which enzymatically remove heparan sulfate proteoglycans, had no effect on basal binding of 125I-hCG to LH receptors or the decrease in binding due to treatment with low bFGF concentrations; however, this treatment dramatically reduced the secondary increase in binding following the addition of higher bFGF concentrations. These results strongly support the idea that the secondary increase in 125I-hCG binding to LH receptors elicited by treatment with higher bFGF concentrations is mediated by bFGF binding to heparan sulfate proteoglycans associated with the plasma membrane and/or extracellular matrix.
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PMID:Basic fibroblast growth factor-induced increase in 125I-human chorionic gonadotropin binding to luteinizing hormone receptors in cultured immature Leydig cells is mediated by binding to heparan sulfate proteoglycans. 814 92

Heparinase I is normally inhibited by an excess or substrate, in this paper we describe that bFGF counteracts the inhibiting effect of the substrate and that heparinase I activity is increased in the presence of bFGF. This effect was observed using heparin concentrations ranging from 10(-9) to 10(-7) M with either a ten fold molar excess or an equimolar concentration of bFGF. In addition, the degree of depolymerization of heparan sulfate produced by heparitinase from Flavobacterium heparinum was increased in the presence of bFGF.
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PMID:Opposite effects of basic fibroblast growth factor and heparin on heparin/heparan sulfate degrading enzymes from Flavobacterium heparinum. 884 52

By radioligand binding followed by Scatchard analysis, we characterized and quantitated the specific binding sites for bFGF on cultured trabecular meshwork cells obtained from freshly enucleated porcine eyes. We detected two binding sites: 1.67 x 10(4) +/- 5.75 x 10(2) high-affinity receptors per cell with a Kd of 33.4 +/- 7.90 pM, and 1.70 x 10(4) +/- 7.57 x 10(5) low-affinity binding sites per cell with a Kd of 3.84 +/- 1.41 nM. At low concentrations of 125I-bFGF (< 1.50 ng ml-1), binding was primarily determined by the high-affinity receptors and, at high concentrations (> 2.50 ng ml-1), binding was dependent on the low-affinity binding sites. By phase-contrast time-lapse video micrography and sequential photomicrography, we demonstrated that at a concentration of 1 ng ml-1, bFGF significantly stimulated the rate of mitosis of the trabecular meshwork cells in G0-phase compared with control cultures maintained in serum-free medium alone. Treatment with higher concentrations of bFGF did not reveal more potent effects on these cells. Our findings demonstrate that trabecular meshwork cells do possess low- and high-affinity receptors for bFGF and that bFGF induces these cells in vitro to re-enter the cell cycle. Because the low-affinity interactions of 125I-bFGF were reduced by 75% following pretreatment of the trabecular meshwork cells with heparinase, these sites represent cell-associated heparin-like molecules and heparan sulfate proteoglycans, and may control the bioavailability of bFGF to ocular tissues. Heparinase treatment also resulted in a 30% reduction in high-affinity binding, which may be secondary to the decreased low-affinity binding. This finding agrees with the well-established scheme for bFGF-receptor interaction. We conclude that bFGF at the concentration present in aqueous humor is capable of stimulating the mitotic activity of trabecular meshwork cells in vitro, suggesting a possible paracrine role of aqueous humour bFGF in vivo. The results obtained in this study, together with our previous findings on bFGF mRNA expression by trabecular meshwork cells and protein deposition in this tissue, also indicates that trabecular cells of the eye may utilize bFGF by an autocrine mechanism.
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PMID:Quantitative characterization of high- and low-affinity binding sites for basic fibroblast growth factor on trabecular cells of the eye. 919 84

Heparinase III degrades heparan sulfate proteoglycans, which are co-receptors for growth factors that stimulate arterial proliferation. We assessed the ability of locally-delivered heparinase III to limit medial vascular smooth muscle cell proliferation induced by balloon catheter injury in rat carotid arteries. Whereas vehicle-treated arteries showed 12% of smooth muscle cells proliferating after 2 days, heparinase III (0.022-5.7 mg/kg) treated arteries showed 0.8-4%. Chemically-inactivated heparinase III did not limit proliferation. In isolated rat A10 vascular smooth muscle cells, heparinase III (1 IU/ml) inhibited both PDGF-BB and bFGF mediated increases in proliferation and migration. These results suggest that heparinase III can limit proliferation by affecting heparan sulfate proteoglycan binding growth factors following arterial injury.
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PMID:Heparinase III limits rat arterial smooth muscle cell proliferation in vitro and in vivo. 969 8

Heparan sulphate from endothelial cells (ECHS) has been shown to bind to bFGF with a lower affinity than that seen for 3T3 fibroblast HS (FHS). To investigate the structural reasons for the low affinity binding of ECHS to bFGF, enzymatic degradation of intact ECHS and FHS chains was undertaken. Filter binding assays showed ECHS heparinase III-resistant fragments 6-7 disaccharides in length and had affinity for bFGF equivalent to that of the intact ECHS chains. The largest resistant fragments from FHS, again 6-7 disaccharides in length, bound to bFGF with a similar affinity to the largest ECHS oligosaccharides, and they therefore have considerably lower affinity than seen for the intact FHS chains. Disaccharide compositional analysis of both ECHS and FHS oligosaccharides showed them to contain similar amounts of 2-O-, 6-O-, and N-sulphated disaccharides. These results suggest that the sulphation pattern within sulphated HS domains and their overall length are not the sole contributors to the binding of intact HS chains to bFGF. It is suggested that domain organisation and frequency of occurrence of large heparinase III-resistant oligosaccharides within intact chains play an important role not only in governing the maximum observed binding affinity of intact chains in the assay system used, but also in the regulation of other biological properties of HS.
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PMID:Endothelial and fibroblast cell-derived heparan sulphate bind with differing affinity to basic fibroblast growth factor. 970 22


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