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)

Constituents of the bone marrow microenvironment have the capacity to influence both normal and malignant hematopoietic cell behavior. For example, HL-60 human promyelocytic leukemia cells in vitro display a more mature phenotype when grown on a bone marrow stroma-derived matrix. To elucidate which component(s) of the stromal matrix is capable of modulating HL-60 cell phenotype, matrices were treated with a variety of chemicals and enzymes prior to being used in the differentiation assay. Treatment of matrices with collagenase, pronase, chondroitinase, or chloroform:methanol:ether could not abolish the differentiation-promoting activity of bone marrow stroma. In contrast, the activity was destroyed by alkali treatment (0.5 M NaOH for 18 h) or heparinase/heparitinase enzymes. Heparin added to cultures increased maturation of HL-60 cells as determined by esterase production, Fc rosette formation, and morphological appearance. Other stromal components such as laminin, fibronectin, collagen I, collagen IV, or chondroitin sulfate did not alter the HL-60 leukemia cell phenotype. Stroma-derived matrix material which labeled with [35S]sulfate and eluted on a DEAE ion-exchange column as a high ionic fraction in 1.5 M LiCl and 7.5% sodium dodecyl sulfate contained the active fraction. A heparan sulfate proteoglycan component isolated by polyacrylamide-agarose gel electrophoresis induced a more mature HL-60 phenotype, and digestion with heparinase/heparitinase in the presence of protease inhibitors abrogated the effects on HL-60 phenotype. We conclude that a heparan sulfate-associated fraction of the bone marrow matrix plays a key role in the regulation of leukemic cell maturation.
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PMID:A heparan sulfate-containing fraction of bone marrow stroma induces maturation of HL-60 cells in vitro. 214 Feb 91

Basic fibroblast growth factor (bFGF) has been identified as an important cytokine for blood cells. To determine whether hematopoietic cells have receptors that recognize bFGF, the ability of human leukemia cell lines to bind 125I-bFGF was investigated. Specific bFGF-binding sites were identified on K562 and HL60 cells, but not on U937 cells. DAMI cells bound low amounts of 125I-bFGF specifically. Binding of 125I-bFGF to K562 cell surfaces was reduced in a dose-dependent manner by unlabeled bFGF or by heparin. Scatchard analysis of binding to K562 cells revealed two classes of binding sites: 1,650 high affinity binding sites per cell with a dissociation constant (kd) of 192 pmol/L, and 36,600 low affinity sites per cell with a kd of 9.3 nmol/L. Chemical crosslinking experiments with K562, HL60, and DAMI cells revealed receptor-growth factor complexes with molecular masses of 140 to 160 kD, similar in size to complexes formed by known receptor species. Binding of 125I-bFGF to K562 cells was sensitive to heparinase treatment but not to chondroitinase treatment, suggesting that heparan sulfate proteoglycans (HSPGs) may be responsible for the low affinity binding sites. To further investigate whether K562 cells make HSPG, the incorporation of 35SO4 into proteoglycans was assessed. Metabolically labeled cell-surface proteoglycans with molecular masses of 180 to 300 kD were identified in K562 cells. These proteoglycans were sensitive to heparinase, demonstrating that K562 cells synthesize bFGF-binding HSPG. Treatment of K562 cells with phorbol-12-myristate-13-acetate (PMA) caused a loss of bFGF-binding capacity. This decreased binding capacity reflected a rapid loss of high affinity receptors. The ability to form bFGF-receptor complexes decreased by 65% to 70% within 1 hour and declined continuously thereafter. The decrease in binding of bFGF was not due to an autocrine downregulation of bFGF receptors, because there was no increase in bFGF after PMA treatment as detected by Western blotting, and suramin, which blocks bFGF binding to receptors, did not prevent the loss of receptors after exposure to PMA. In addition, inhibitors of either protein synthesis or protease activity did not prevent the loss of bFGF receptors in PMA-treated cells. In summary, this work demonstrates that leukemia cell lines have receptors that specifically bind bFGF and supports the hypothesis that bFGF acts directly on certain blood cells to stimulate their proliferation.
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PMID:Human leukemia cell lines bind basic fibroblast growth factor (FGF) on FGF receptors and heparan sulfates: downmodulation of FGF receptors by phorbol ester. 854 48

Cellular entry of human T-cell leukaemia virus type 1 (HTLV-1) was studied by a quantitative assay system using vesicular stomatitis virus (VSV) pseudotypes in which a recombinant VSV (VSVDeltaG*) containing the gene for green fluorescent protein instead of the VSV G protein gene was complemented with viral envelope glycoproteins in trans. Most of the cell lines tested showed susceptibility to VSVDeltaG* complemented with either HTLV-1 envelope glycoproteins (VSVDeltaG*-Env) or VSV G protein (VSVDeltaG*-G), but not to VSVDeltaG* alone, indicating that cell-free HTLV-1 could infect many cell types from several species. High concentration pronase treatment of cells reduced their susceptibility to VSVDeltaG*-Env, while trypsin treatment, apparently, did not. Treatment of the cells with sodium periodate, heparinase, heparitinase, phospholipase A2 or phospholipase C reduced the susceptibility of cells to VSVDeltaG*-Env, but not to VSVDeltaG* complemented with measles virus (Edmonston strain) H and F proteins (VSVDeltaG*-EdHF), which was used as a control. Purified phosphatidylcholine also inhibited the infectivity of VSVDeltaG*-Env, but not VSVDeltaG*-G. These findings indicated that, in addition to cell surface proteins, glycosaminoglycans and phospholipids play an important role in the process of cell-free HTLV-1 entry.
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PMID:Analysis of the molecules involved in human T-cell leukaemia virus type 1 entry by a vesicular stomatitis virus pseudotype bearing its envelope glycoproteins. 1125 87

Non-infectious, envelope protein-free, retrovirus-like particles (VLP) derived from either Moloney murine leukemia virus (MLV) or human HIV are able to bind efficiently to, but not infect, target cells. Upon subsequent addition to the bound particles of the G protein of vesicular stomatitis virus (VSV-G), an efficient surrogate retrovirus envelope protein, the VLP are efficiently taken up by the cells to produce infection. Cell attachment of the VLP is efficiently inhibited by soluble heparin and dextran sulfate and less efficiently abrogated by several other glycosaminoglycans (GAGs) including chondroitin sulfate A and chondroitin sulfate B (dermatan sulfate), as determined by deconvolution microscopic immunodetection of the viral gag protein and by quantitative binding studies of metabolically labeled (35)S-VLP. Enzymatic digestion of heparan sulfate (HS) from the cell surface with heparinase I also reduces VLP binding. Furthermore, VLP adsorption onto several CHO cell lines variably deficient in cell surface GAG is significantly but incompletely abrogated. De-sulfated heparins are less efficient than native heparin in inhibiting the Polybrene-mediated binding of VLP, whereas growth of human cells in the presence of sodium chlorate leads to significant reduction of Polybrene-mediated VLP binding. In addition, specific inhibition of VLP binding and infectivity of mature infectious VSV-G-pseudotyped virus is observed in the presence of heparin and HS under Polybrene-free conditions. We conclude from these studies that the presence of Polybrene, the degree of sulfation of cell surface GAG, and possibly the presence of charged cell surface macromolecules create an electrostatic environment that promotes optimum binding of VLP to cells. Additionally, our results demonstrate that, in the absence of Polybrene, initial attachments of non-infectious, envelope protein-free VLP and probably mature infectious virus particles are mediated by interactions of the virus particles with cell surface heparan sulfate, and possibly with other GAG molecules.
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PMID:Cell surface heparan sulfate is a receptor for attachment of envelope protein-free retrovirus-like particles and VSV-G pseudotyped MLV-derived retrovirus vectors to target cells. 1199 44

Target cell entry of murine leukaemia virus vectors proceeds via primary attachment, independent of the viral envelope protein and subsequent envelope-receptor interaction. Although much attention has been paid to modifying the latter for target cell specificity, the initial binding interaction has been overlooked, despite its opposing involvement both in providing the virus available for receptor binding and in depleting free virus. As a first step towards modifying primary attachment, both to provide specificity and to enhance vector availability, we sought to determine the nature of this interaction. Following an initial screen of GAGs (glycosaminoglycans) for their ability to inhibit virus binding and transduction, we have shown that production of virus from cells in which GAG sulfation is inhibited, or treatment of virus with heparinase III, reduces both particle attachment and infection. Detection in purified virus preparations of a neo-epitope generated by heparinase III confirmed the presence of virus-associated HSPG [HS (heparan sulfate) proteoglycan], acquired from the producer cell. We propose that host-acquired cell-surface HSPG (potentially including syndecan-2) provides a means of virus attachment to target cells that precedes specific receptor interaction and membrane fusion. Inhibition of HS biosynthesis may provide a sufficiently reduced background of primary binding such that novel mechanisms of attachment, ideally with appropriate target cell specificity, can be introduced.
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PMID:Primary attachment of murine leukaemia virus vector mediated by particle-associated heparan sulfate proteoglycan. 1689 23

Three molecules have been identified as the main cellular factors required for binding and entry of human T-cell leukemia virus type 1 (HTLV-1): glucose transporter 1 (GLUT1), heparan sulfate (HS), and neuropilin 1 (NRP-1). However, the precise mechanism of HTLV-1 cell tropism has yet to be elucidated. Here, we examined the susceptibilities of various human cell lines to HTLV-1 by using vesicular stomatitis virus pseudotypes bearing HTLV-1 envelope proteins. We found that the cellular susceptibility to HTLV-1 infection did not correlate with the expression of GLUT1, HS, or NRP-1 alone. To investigate whether other cellular factors were responsible for HTLV-1 susceptibility, we conducted expression cloning. We identified two HS proteoglycan core proteins, syndecan 1 and syndecan 2, as molecules responsible for susceptibility to HTLV-1. We found that treatment of syndecan 1-transduced cells (expressing increased HS) with heparinase, a heparin-degradative enzyme, reduced HTLV-1 susceptibility without affecting the expression levels of HS chains. To further elucidate these results, we characterized the expression of HS chains in terms of the mass, number, and length of HS in several syndecan 1-transduced cell clones as well as human cell lines. We found a significant correlation between HTLV-1 susceptibility and the number of HS chains with short chain lengths. Our findings suggest that a combination of the number and the length of HS chains containing heparin-like regions is a critical factor which affects the cell tropism of HTLV-1.
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PMID:Entry of human T-cell leukemia virus type 1 is augmented by heparin sulfate proteoglycans bearing short heparin-like structures. 2223 10

Despite the increasing availability of new classes of cancer treatment, such as immune- and targeted therapies, there remains a need for the development of new antiproliferative/cytotoxic drugs with improved pharmacological profiles that can also overcome drug resistant forms of cancer. In this study, we have identified, and characterised, a novel marine polysaccharide with the potential to be developed as an anticancer agent. Sulphated polysaccharides isolated from the common cockle (Cerastoderma edule) were shown to have antiproliferative activity on chronic myelogenous leukaemia and relapsed acute lymphoblastic leukaemia cell lines. Disaccharide and monosaccharide analysis of these marine polysaccharides confirmed the presence of glycosaminoglycan-like structures that were enriched in ion-exchange purified fractions containing antiproliferative activity. The antiproliferative activity of these glycosaminoglycan-like marine polysaccharides was shown to be susceptible to heparinase but not chondrotinase ABC digestion. This pattern of enzymatic and antiproliferative activity has not previously been seen, with either marine or mammalian glycosaminoglycans. As such, our findings suggest we have identified a new type of marine derived heparan sulphate/heparin-like polysaccharide with potent anticancer properties.
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PMID:Antiproliferative Activity of Glycosaminoglycan-Like Polysaccharides Derived from Marine Molluscs. 2946 90

Variants of Ross River virus (RRV) that bind to heparan sulfate (HS) were previously selected by serial passaging in cell culture. To explore the effects of mutations that convey HS utilization, we pseudotyped Moloney murine leukemia virus (MoMLV), with the RRV envelope. We substituted amino-acid residues 216 and 218 on RRV-E2-envelope glycoprotein with basic amino-acid residues, because these mutations confer affinity for HS upon RRV. However, T216R-RRV- and N218R-RRV-pseudotyped viruses possessed lower transduction titers, and we demonstrated that HS-affinity impeded release of pseudotyped virus from producer cells. Addition of heparinase to HS-expressing target cells reduces the transduction efficiency of the T216R-RRV- and N218R-RRV-pseudotyped viruses, whereas no such effect is seen in cells lacking HS. Under appropriate conditions, these T216R-RRV- and N218R-RRV-pseudotyped viruses have enhanced capacities for transducing HS-expressing cells. General principles concerning viral adaptation to the use of attachment factors and design of pseudotyped viral vectors are discussed.
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PMID:Role of heparan sulfate in entry and exit of Ross River virus glycoprotein-pseudotyped retroviral vectors. 3071 79