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 binding of heparin-binding EGF-like growth factor (HB-EGF) to the epidermal growth factor (EGF) receptor of human endometrial carcinoma cells was compared to that of EGF using an 125I-EGF radioreceptor assay. The inhibitory effect of HB-EGF on 125I-EGF binding was reversed either in the presence of heparin (but not by chondroitin sulfate) or by pre-treating the cells with heparinase. These treatments did not affect the binding of EGF to its receptor. To map potential regions in the HB-EGF molecule that mediate its heparin-dependent interaction with the EGF receptor, HB-EGF peptides were synthesized that were non-homologous to EGF. Accordingly residues 20-25 and 36-41, but not residues 8-19, of HB-EGF were found to be (i) heparin-binding and (ii) modulators of HB-EGF (but not of EGF) binding to the EGF receptor.
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PMID:Interaction of heparin-binding EGF-like growth factor (HB-EGF) with the epidermal growth factor receptor: modulation by heparin, heparinase, or synthetic heparin-binding HB-EGF fragments. 130 84

We have isolated cDNA clones that code for a proteoglycan-related polypeptide with unique properties. A lambda gt11 expression library made from human fibroblast mRNA was screened with an antiserum made against a proteoglycan fraction from human fetal membranes. One group of positive clones revealed an open reading frame coding for 685 amino acids from the COOH terminus of a polypeptide. This amino acid sequence contains a domain that is strongly homologous with the COOH-terminal core protein domain of the large aggregating cartilage proteoglycan. This domain also contains sequences that are homologous with vertebrate lectins that bind terminal galactosyl, N-acetyl-glucosaminyl or mannosyl residues. On the NH2-terminal side of the lectin-like domain the cDNA-derived amino acid sequence contains two epidermal growth factor-related segments. The cDNA clones were shown to belong to a chondroitin sulfate proteoglycan by using antisera made against two peptides predicted from the cDNA sequence. These antisera were reactive with a proteoglycan fraction from fibroblasts after chondroitinase treatment of the fraction but not after treatment with heparinase or no treatment. Among the several polypeptides reactive with the anti-peptide antibodies the largest one, corresponding to a molecular weight of about 400,000, is likely to be the intact core protein, whereas the smaller polypeptides may be processing products or products of artifactual proteolysis. These results show that the amino acid sequence belongs to a proteoglycan core protein, and the sequence, therefore, provides a molecular definition to this proteoglycan. The lectin-related and growth factor-like sequences in the core protein of this proteoglycan suggest that it may play a role in intercellular signaling.
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PMID:A fibroblast chondroitin sulfate proteoglycan core protein contains lectin-like and growth factor-like sequences. 282 Sep 64

Cytotactin/tenascin is a multidomain extracellular matrix protein that inhibits both cell spreading and intracellular alkalinization. The protein has multiple different domains which are homologous to regions in epidermal growth factor, fibronectin, and fibrinogen. In previous studies, we produced nonoverlapping fusion proteins corresponding to these domains and examined their effects on cell attachment and spreading. Based on their ability either to promote or to inhibit cell attachment, two of these fusion proteins were shown to be adhesive and two were shown to be counteradhesive. To determine how the adhesive and counteradhesive activities of different cytotactin/tenascin domains alter intracellular pH (designated pHi), we have measured pHi, in NIH3T3 and U251MG cells in the presence of the cytotactin/tenascin fusion proteins and intact cytotactin/tenascin, as well as fibronectin. Cells incubated in the presence of intact cytotactin/tenascin or of the counteradhesive fusion proteins had a pHi lower than control cells. In contrast, the presence of the adhesive fusion proteins or of fibronectin caused cells to have higher pHi values than control cells. When two fragments were simultaneously presented, one of which alone increased pHi and the other of which alone decreased pHi, the predominant effect was that of lowered pHi. Incubation with an RGD-containing peptide derived from the cytotactin/tenascin sequence inhibited alkalinization promoted by the adhesive fragment containing the second through sixth fibronectin type III repeats that was known to bind to integrins. Incubation of the cells with heparinase I or III inhibited the intracellular alkalinization of cells plated in the presence of the other adhesive fusion protein containing the fibrinogen domain, suggesting that heparan sulfate proteoglycans were involved in these pHi changes. The activity of protein kinase C appeared to be important for the changes in pHi mediated by all of the proteins. The protein kinase C inhibitor Calphostin C blocked the rise in pHi elicited by the adhesive fusion proteins and by fibronectin. Moreover, activation of protein kinase C by the addition of phorbol esters increased the pHi in cells plated on cytotactin/tenascin or counteradhesive fusion proteins and reversed their effects. The results of this study support the hypothesis that cytotactin/tenascin can bind to multiple cell surface receptors and thereby elicit different physiological responses. Decreases in pHi are correlated with the phenomenon of counteradhesion whereas the ability to increase pHi is associated with cell attachment via at least two different types of cell surface receptors. The data raise the possibility that binding of cytotactin/tenascin may influence primary cellular processes such as migration and proliferation through the differential regulation of pHi.
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PMID:Differential effects of cytotactin/tenascin fusion proteins on intracellular pH and cell morphology. 752 16

Human amphiregulin (AR) is a heparin-binding growth factor which functions by binding to and activating the epidermal growth factor (EGF) receptor tyrosine kinase. AR contains an EGF-like domain (residues 44-84) and a Lys/Arg-rich NH2-terminal extension (residues 1-43). Synthetic peptides corresponding to residues 8-26, 26-44, and 68-84 of AR were tested for their ability to compete for the binding of AR to immobilized heparin. AR8-26 and AR68-84 had no significant effect on the binding of AR to heparin, whereas AR26-44 bound to heparin and blocked the binding of AR to heparin. Both soluble heparin and heparan sulfate inhibited AR-induced mitogenesis in MCF-10A human mammary epithelial cells with an IC50 of 5 and 2 micrograms/ml, respectively, whereas soluble chondroitin sulfate had only a slight inhibitory effect. When MCF-10A cells were grown in the presence of chlorate, an inhibitor of sulfation, or exposed to the glycosaminoglycan-degrading enzymes heparitinase or heparinase, the ability of AR to evoke mitogenesis in these cells was lost. Chlorate, heparitinase, or heparinase treatment inhibited AR-induced autophosphorylation of tyrosine residues in the EGF receptor. None of these treatments had any significant effect on EGF-triggered mitogenic signaling by the EGF receptor. These results indicate that extracellular heparan sulfate glycosaminoglycan is essential to AR-induced mitogenic signaling by the EGF receptor tyrosine kinase.
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PMID:Heparan sulfate is essential to amphiregulin-induced mitogenic signaling by the epidermal growth factor receptor. 792 59

Previous studies have shown that heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) mRNA is synthesized in the mouse uterine luminal epithelium temporally, just prior to implantation, and spatially, only at the site of blastocyst apposition (Das, S. K., Wang, X. N., Paria, B. C., Damm, D., Abraham, J. A., Klagsbrun, M., Andrews, G. K. and Dey, S. K. (1994) Development 120, 1071-1083). HB-EGF is synthesized as a transmembrane protein (HB-EGF TM) that can be processed to release the soluble growth factor. An antibody that cross-reacts only with the transmembrane form detected HB-EGF TM in uterine luminal epithelium in a spatial manner similar to that of HB-EGF mRNA. HB-EGF TM is a juxtacrine growth factor that mediates cell-cell contact. To ascertain if HB-EGF TM could be an adhesion factor for blastocysts, a mouse cell line synthesizing human HB-EGF TM was co-cultured with mouse blastocysts. Cells synthesizing HB-EGF TM adhered to day-4 mouse blastocysts more extensively than parental cells or cells synthesizing a constitutively secreted form of HB-EGF. Adhesion of cells synthesizing HB-EGF TM to blastocysts was inhibited by excess recombinant HB-EGF but less so by TGF-alpha. Adhesion was also inhibited by the synthetic peptide P21 corresponding to the HB-EGF heparin binding domain, and by incubating the blastocysts with heparinase. In addition, adhesion to delayed implanting dormant blastocysts, which lack EGF receptor (EGFR), was diminished relative to normal blastocysts. These results suggested that adhesion between blastocysts and cells synthesizing HB-EGF TM was mediated via interaction with both blastocyst EGFR and heparan sulfate proteoglycan (HSPG). It was concluded that HB-EGF TM, which is synthesized exclusively in the luminal epithelium at the site of blastocyst apposition, and which is a juxtacrine adhesion factor for blastocysts, could be one of the mediators of blastocyst adhesion to the uterus in the process of implantation.
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PMID:Mouse preimplantation blastocysts adhere to cells expressing the transmembrane form of heparin-binding EGF-like growth factor. 862 15

Basic fibroblast growth factor (bFGF) and its specific receptors have diverse roles on a variety of cell types, such as the induction of vascular smooth-muscle cell proliferation which contributes to restenosis after coronary balloon angioplasty. bFGF is also known to interact with heparan sulphate proteoglycans present on the cell surface or in the extracellular matrix. In this study, the binding of 125I-bFGF to human aortic smooth-muscle cells was investigated. 125I-bFGF binding to these cells was reversible and saturable. Scatchard analysis revealed the presence of two distinct binding sites: a high-affinity receptor (Kd=38+/-7 pM; 1480+/-220 sites/cell) and a low-affinity non-saturable binding site (Kd=8. 0+/-2.0 nM). Pretreatment of the cells with heparinase resulted in a large reduction of 125I-bFGF binding to its low-affinity receptors, suggesting that they are heparin-like molecules. The specificity of the low- and high-affinity binding sites for bFGF was determined with acidic FGF, platelet-derived growth factor-BB and epidermal growth factor, which did not compete for 125I-bFGF binding. Expression of FGF receptor isoforms analysed by reverse transcriptase-PCR revealed the presence of only the type-1 receptor. Binding to low-affinity binding sites was antagonized by heparin, suramin, protamine sulphate and platelet factor 4. Unexpectedly, these molecules also reduced the binding of 125I-bFGF to its high-affinity sites. Consistent with these results, heparin, suramin, protamine sulphate and platelet factor 4 inhibited bFGF-induced proliferation of human aortic smooth-muscle cells. Heparin abrogated bFGF-induced release of tissue-type plasminogen activator by these cells. These observations suggest that the interaction of bFGF with human aortic smooth-muscle cells is different from that described for other cells such as endothelial cells, in which heparin acts as a potentiating factor of the mitogenic activity of bFGF.
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PMID:Heparin inhibits the binding of basic fibroblast growth factor to cultured human aortic smooth-muscle cells. 930 14

The role of cell density in modulating basic fibroblast growth factor binding and activity was investigated. A primary corneal stromal fibroblast cell culture system was used, since these cells do not constitutively express heparan sulfate proteoglycans in vivo except after injury. A 3-5-fold reduction in bFGF binding per cell was observed as cell density increased from 1000 to 35,000 cells/cm2. The cell density-dependent change in bFGF binding was not the result of altered FGFR expression as determined by equilibrium binding experiments and by immunoblot analysis. However, bFGF-cell surface receptor binding affinities were measured to be 10-20-fold higher at low cell densities than at intermediate and high cell density. bFGF-induced cell proliferation was also cell density-dependent, with maximal stimulation of proliferation 190-280% greater at intermediate densities (15,000 cells/cm2) than at other cell densities. This effect was specific to bFGF as serum, epidermal growth factor, and transforming growth factor-beta did not exhibit the same density-dependent profile. Further, heparan sulfate proteoglycans and, specifically, syndecan-4 were implicated as the modulator of bFGF binding and activity. Pretreatment of cell cultures with heparinase resulted in reduced bFGF binding to the cells and abrogated bFGF induced proliferation. These data suggest a mechanism by which cell density regulates heparan sulfate proteoglycan expression and modulates the cellular response to bFGF. Modulation of heparan sulfate proteoglycan expression might be an important aspect of the regulation of stromal cell migration and proliferation during wound healing.
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PMID:Regulation of basic fibroblast growth factor binding and activity by cell density and heparan sulfate. 1022 22

Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) stimulates cell proliferation in the adult mammalian brain, but the mechanism involved is unknown. To address this issue we treated mouse brain cerebral cortical cultures enriched in neuronal precursors with full-length HB-EGF, its HB or EGF-like domain alone, or both domains in combination. Labeling of cultures with bromodeoxyuridine (BrdU), a marker of cell proliferation, was increased approximately 10% by the HB domain and approximately 20% by the EGF-like domain, and the effects of the two domains were additive. Full-length HB-EGF was most effective (approximately 50% increase) in stimulating BrdU incorporation. Preincubation with heparinase III or with Na-chlorate abolished cell proliferation induced by HB-EGF, consistent with dependence on cell-surface heparan sulfate proteoglycans. The effect of HB-EGF was also blocked by the EGF receptor (EGFR/ErbB1) inhibitors PD153035 and PD158780, implicating EGFR in HB-EGF-induced cell proliferation. The phosphatidylinositol 3'-kinase (PI3K) inhibitors LY294002 and wortmannin, and the MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitors U0126 and PD98059, reduced HB-EGF-induced BrdU incorporation into cultures, and HB-EGF enhanced phosphorylation of Akt and ERK, implying a role for PI3K/Akt and MEK/ERK signaling in HB-EGF-stimulated cell proliferation. These findings help to clarify the molecular mechanisms through which HB-EGF operates.
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PMID:Heparin-binding epidermal growth factor-like growth factor stimulates cell proliferation in cerebral cortical cultures through phosphatidylinositol 3'-kinase and mitogen-activated protein kinase. 1595 78