Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied alteration of glycosaminoglycans (GAGs) induced by recombinant human tumor necrosis factor alpha (rhTNF alpha) in vascular smooth-muscle cells from bovine aorta in a culture system. It was found that rhTNF alpha at 10 ng/ml and below significantly increased the incorporation of [35S]sulfate (35S) but conversely decreased that of [3H]glucosamine (3H) into GAGs in the trypsinate fraction of the cell layer after a 24-h incubation. These results suggested that rhTNF alpha reduced the formation and/or the anchorage of sugar chains in the cell layer but enhanced their sulfation in whole GAG synthesis by the cells. In results, the ratio of 35S to 3H in the GAGs was markedly increased. This increase occurred after 24 h and longer when the cells were treated with 1.0 ng/ml rhTNF alpha. The TNF alpha-induced alteration of the incorporation of both 35S and 3H was completely blocked by anti-rhTNF alpha antibody. Other cytokines including recombinant human interleukin-1 beta and -6, and platelet-derived growth factor failed to alter the ratio of 35S to 3H in the GAGs of the trypsinate fraction of the cell layer. In cultured vascular endothelial cells from bovine aorta, however, rhTNF alpha at 1.0 ng/ml significantly decreased the incorporation of both 35S and 3H into GAGs of both the trypsinate fraction and the medium; the ratio of 35S to 3H was not changed. Characterization of GAGs in vascular smooth muscle cell trypsinate fraction revealed that rhTNF alpha at 10 ng/ml induced (i) no change of the incorporation of 3H in the hyaluronate fraction, (ii) a marked increase in the incorporation of 35S and no change of that of 3H in chondroitin sulfates (A plus C) fraction, (iii) a significant decrease in the incorporation of both 35S and 3H in the heparan sulfate fraction, and (iv) no change of the incorporation of 35S and a marked decrease in that of 3H in the dermatan sulfate fraction. In the medium, rhTNF alpha also induced various changes of GAGs. It was therefore concluded that TNF alpha may have a capacity of inducing a qualitative change of vascular smooth-muscle cell GAGs, which may be involved in the vascular pathology such as atherosclerosis.
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PMID:Tumor necrosis factor alpha-induced alteration of glycosaminoglycans in cultured vascular smooth-muscle cells. 845 75

Heparan sulfate proteoglycans produced by vascular endothelium may function physiologically to restrain the migration, multiplication, and phenotypic transition of vascular smooth-muscle cells, and to maintain an anticoagulant luminal surface by bonding and activating antithrombin III. Thus, ample production of heparan sulfate proteoglycans may act to prevent atherosclerosis and its thrombotic complications. The ability of exogenous heparin to stimulate synthesis of heparan sulfate proteoglycans by vascular endothelium may be largely responsible for the positive outcomes of most controlled evaluations of low-dose heparin as a long-term therapy for coronary disease. Glucosamine, a biosynthetic precursor of mucopolysaccharides, can substantially enhance mucopolysaccharide production when added to cultured fibroblasts or chondrocytes; the clinical utility of oral glucosamine in osteoarthritis may reflect increased synthesis of cartilage proteoglycans. It is reasonable to speculate that exogenous glucosamine will likewise enhance heparan sulfate proteoglycans production by vascular endothelial cells, and, when administered orally in regimens comparable to those effective in osteoarthritis, will thereby act to retard atherogenesis.
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PMID:Glucosamine may retard atherogenesis by promoting endothelial production of heparan sulfate proteoglycans. 914 Aug 89

Coronary bypass vessels, saphenous vein (SV) and internal thoracic artery (ITA), differ in susceptibility to atherosclerosis and medium- to long-term patency. Whereas most ITA remain patent (90% at 10 years), 20% of SV grafts fail in the first year and approximately 45% fail within 10 years. Reasons for these differences are not fully understood. Loss of SV patency may reflect early metabolic events, particularly increased proteoglycan (PG) synthesis which contributes to intimal volume and promotes atherogenesis through retention of atherogenic lipoproteins. We determined, in vitro, the PG metabolic activity of SV, ITA, and human coronary arteries through autoradiographic detection of incorporated [3H]glucosamine. SV had significantly higher levels of PG synthesis than ITA, especially in the subendothelial zone and after time (7 days) in culture. Patterns of synthesis in coronary vessels were similar to SV with high levels of incorporation in the subendothelial zone of thickened intima (> 100 microm). Increased subendothelial labelling in SV was due to increased PG synthesis, not decreased degradation. ITA showed no propensity for upregulation of subendothelial PG synthesis. Immunohistochemistry showed TGF-beta1 and TGF-beta2 localised primarily to the subendothelial zone of SV and coronary arteries. With time in culture immunostaining increased in parallel with increased PG synthesis. Subendothelial TGF-beta1 and TGF-beta2 were absent in ITA. A panspecific TGF-beta neutralising antibody reduced subendothelial PG synthesis in SV and coronary arteries by 50 and 60%, respectively. These results support the idea that vessels susceptible to atherosclerosis show increased accumulation of subendothelial PG mediated by TGF-beta.
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PMID:Subendothelial proteoglycan synthesis and transforming growth factor beta distribution correlate with susceptibility to atherosclerosis. 934 30

Heparan sulfate is thought to regulate the biological activities of several proteins implicated in the pathogenesis of atherosclerosis. While the interactions of heparan sulfate with lipoprotein lipase and various growth factors have been actively studied, little is known of the cellular regulation of heparan sulfate biosynthesis in response to lipid accumulation. We have investigated heparan sulfate biosynthesis during conversion of murine J774 macrophages into lipid-laden foam cells. Such conversion is shown to accelerate the rate of glycosaminoglycan synthesis and the transport of newly synthesized proteoglycans into the medium. Moreover, the structure of heparan sulfate is specifically altered due to an approximately 30% increase in the 6-O-sulfation of glucosamine residues within the N-sulfated heparan sulfate domains, whereas the sulfation of chondroitin sulfate remains unaffected. These results suggest a selective effect of foam cell conversion on the biosynthesis of heparan sulfate.
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PMID:Foam cell conversion of macrophages alters the biosynthesis of heparan sulfate. 964 72

Reduced heparin and heparan sulfate (HS) proteoglycans (PG) have been observed in both inflammation and atherosclerosis. Methods to increase endogenous heparin and heparan sulfate are not known. We found that incubation of endothelial cells with 500-1,000 micrograms/ml high density lipoprotein (HDL) increased 35SO4 incorporation into PG by 1.5-2.5-fold. A major portion of this increase was in HS and was the result of increased synthesis. Total PG core proteins were not altered by HDL; however, the ratio of 35SO4 to [3H]glucosamine was increased by HDL, suggesting increased sulfation of glycosaminoglycans. In addition, HDL increased the amount of highly sulfated heparin-like HS in the subendothelial matrix. HS from HDL-treated cells bound 40 +/- 5% more 125I-antithrombin III (requires 3-O sulfated HS) and 49 +/- 3% fewer monocytes. Moreover, the HS isolated from HDL-treated cells inhibited smooth muscle cell proliferation (by 83 +/- 5%) better than control HS (56 +/- 6%) and heparin (42 +/- 6%). HDL isolated from apolipoprotein E (apoE)-null mice did not stimulate HS production unless apoE was added. ApoE also stimulated HS production in the absence of HDL. ApoE did not increase 35SO4 incorporation in macrophages and fibroblasts, suggesting that this is an endothelial cell-specific process. Receptor-associated protein inhibited apoE-mediated stimulation of HS only at higher (20 micrograms/ml) doses, suggesting the involvement of a receptor-associated protein-sensitive pathway in mediating apoE actions. In summary, our data identify a novel mechanism by which apoE and apoE-containing HDL can be anti-atherogenic. Identification of specific apoE peptides that stimulate endothelial heparin/HS production may have important therapeutic applications.
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PMID:Apolipoprotein E containing high density lipoprotein stimulates endothelial production of heparan sulfate rich in biologically active heparin-like domains. A potential mechanism for the anti-atherogenic actions of vascular apolipoprotein e. 998 21

Estrogen deficiency, hyperinsulinemia, type II diabetes, atherosclerosis, and a past history of elevated blood pressure may be associated with increased risk of Alzheimer's disease (AD). Common to all of these risk factors is a diminished capacity of vascular endothelium to generate nitric oxide (NO). Vascular NO has the potential to enhance the membrane polarization of cerebral neurons by increasing the open probability of calcium-activated potassium channels; this may protect neurons from the excessive calcium influx, potentiated by beta-amyloid peptides that is thought to mediate neuronal damage in AD. The possibility that NO/cyclic guanosine 3', 5'-phosphate (cGMP) may modulate the synthesis or processing of the amyloid precursor protein, also merits evaluation. Practical measures for promoting vascular NO production may include increased intakes of arginine, potassium, antioxidants, and fish-oil, as well as lifestyle measures that typically lower elevated blood pressure; potential benefits of chromium, glucosamine, and silicon should also be explored. In hypertensives, angiotensin-converting enzyme (ACE) inhibitors and sodium restriction may favorably influence endothelial function. Fish-oil should have the additional benefit of antagonizing the contribution of interleukin-1 to AD pathogenesis. Ancillary anti-excitotoxic measures such as magnesium, taurine, phenytoin, and vasodilators targeting ATP-dependent potassium (KATP) channels, may likewise reduce AD risk. Most of the nutritional measures suggested here would in any case be recommendable for preservation of vascular health.
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PMID:Vascular nitric oxide may lessen Alzheimer's risk. 1005 65

Ulcerative colitis, Crohn's disease and interstitial cystitis share many common features, the most important of which is a defect in the glycoaminoglycan (GAG) defensive barrier. This defect allows penetration of toxins causing localized inflammatory response, followed by fibrosis and distant pathological changes, together with a myriad of biochemical and immunological changes. The latter has caused confusion as to etiology of the aforementioned disorders. This hypothesis is somewhat supported by the fact that agents such as glucosamine and pentosan polysulphate (Elmiron) that replace the GAG layer, improve the conditions. The potential for extrapolation of this hypothesis to atherosclerosis and arthropathies exists. There is a great danger in modern medical research that if one misses the wood for the trees, one becomes hopelessly lost in the minutiae of research. At present, it is embarrassing that ulcerative colitis (UC), Crohn's (CR) and interstitial cystitis (IC) are the cause of a great deal of morbidity and occasionally mortality, yet after intensive research, the etiology and effective treatment eludes us. The research in the past has focused extensively on inflammatory response in the mucosal lining, and biochemical, infective and immunological changes in the serum. This has led to a vast array of research pathways that seem at the present time to be totally lost and, might I say, aimless in direction, as a cause for these conditions, that remain amongst the most imperically treated in modern medicine. Another possible syndrome in this class would be Reiter's, which has many features in common with the above. The basic tenet of a GAG deficiency hypothesis is that, as shown in Figure 1A, an intact GAG layer provides, firstly, a mechanical and electrostatic defence against penetration of infective agents, toxins, antigenic protein moieties, etc. and, secondly, the prevention of extravasation of body fluid components. A degraded GAG layer is the start of the disease cascade of the above group of illnesses.
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PMID:Glycoaminoglycan (GAG) deficiency in protective barrier as an underlying, primary cause of ulcerative colitis, Crohn's disease interstitial cystitis and possibly Reiter's syndrome. 1046 66

Vascular smooth muscle cells play a key role in the development of atherosclerosis. Culture of vascular smooth muscle A10 cells with high glucose for 4 weeks enhanced platelet-derived growth factor (PDGF)-induced BrdU incorporation. Since a long period of high glucose incubation was required for the effect, and it was inhibited by co-incubation with azaserine, the role of hexosamine biosynthesis in the development of atherosclerosis in diabetes was studied in A10 cells. Addition of glucosamine to the culture media enhanced PDGF-stimulated BrdU incorporation, and PDGF-induced tyrosine phosphorylation of the PDGF beta-receptor was increased by glucosamine treatment. Of the subsequent intracellular signaling pathways, PDGF-induced PDGF beta-receptor association with PLC gamma was not affected, whereas tyrosine phosphorylation of Shc, subsequent association of Shc with Grb2, and MAP kinase activation were relatively decreased. In contrast, PDGF-induced PDGF beta-receptor association with the p85 regulatory subunit of PI3-kinase and PI3-kinase activation were increased by 20% (P<0.01) and 36% (P<0.01), respectively. The intracellular signaling molecules responsible for the glucosamine effect were further examined using pharmacological inhibitors. Pretreatment with PLC inhibitor (U73122) had negligible effects, and MEK1 inhibitor (PD98059) showed only a slight inhibitory effect on the PDGF-induced BrdU incorporation. In contrast, pretreatment with PI3-kinase inhibitor (LY294002) significantly inhibited glucosamine enhancement of PDGF-induced BrdU incorporation. These findings suggest that glucosamine is involved in the development of atherosclerosis by enhancing PDGF-induced mitogenesis specifically via the PI3-kinase pathway.
Atherosclerosis 2001 Aug
PMID:Glucosamine enhances platelet-derived growth factor-induced DNA synthesis via phosphatidylinositol 3-kinase pathway in rat aortic smooth muscle cells. 1147 33

Defective binding of apolipoprotein E (apoE) to heparan sulfate proteoglycans (HSPGs) is associated with increased risk of atherosclerosis due to inefficient clearance of lipoprotein remnants by the liver. The interaction of apoE with HSPGs has also been implicated in the pathogenesis of Alzheimer's disease and may play a role in neuronal repair. To identify which residues in the heparin-binding site of apoE and which structural elements of heparan sulfate interact, we used a variety of approaches, including glycosaminoglycan specificity assays, (13)C nuclear magnetic resonance, and heparin affinity chromatography. The formation of the high affinity complex required Arg-142, Lys-143, Arg-145, Lys-146, and Arg-147 from apoE and N- and 6-O-sulfo groups of the glucosamine units from the heparin fragment. As shown by molecular modeling, using a high affinity binding octasaccharide fragment of heparin, these findings are consistent with a binding mode in which five saccharide residues of fully sulfated heparan sulfate lie in a shallow groove of the alpha-helix that contains the HSPG-binding site (helix 4 of the four-helix bundle of the 22-kDa fragment). This groove is lined with residues Arg-136, Ser-139, His-140, Arg-142, Lys-143, Arg-145, Lys-146, and Arg-147. In the model, all of these residues make direct contact with either the 2-O-sulfo groups of the iduronic acid monosaccharides or the N- and 6-O-sulfo groups of the glucosamine sulfate monosaccharides. This model indicates that apoE has an HSPG-binding site highly complementary to heparan sulfate rich in N- and O-sulfo groups such as that found in the liver and the brain.
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PMID:New insights into the heparan sulfate proteoglycan-binding activity of apolipoprotein E. 1150 May

Endothelial nitric oxide synthase (eNOS) is activated by phosphorylation of serine 1177 by the protein kinase Akt/PKB. Since hyperglycemia-induced mitochondrial superoxide overproduction increases O-linked N-acetylglucosamine modification and decreases O-linked phosphorylation of the transcription factor Sp1, the effect of hyperglycemia and the hexosamine pathway on eNOS was evaluated. In bovine aortic endothelial cells, hyperglycemia inhibited eNOS activity 67%, and treatment with glucosamine had a similar effect. Hyperglycemia-associated inhibition of eNOS was accompanied by a twofold increase in O-linked N-acetylglucosamine modification of eNOS and a reciprocal decrease in O-linked serine phosphorylation at residue 1177. Both the inhibition of eNOS and the changes in its post-translational modifications were reversed by antisense inhibition of glutamine:fructose-6-phosphate amidotransferase, the rate-limiting enzyme of the hexosamine pathway, or by blocking mitochondrial superoxide overproduction with uncoupling protein-1 (UCP-1) or manganese superoxide dismutase (MnSOD). Immunoblot analysis of cells expressing myc-tagged wild-type human eNOS confirmed the reciprocal increase in O-linked N-acetylglucosamine and decrease in O-linked serine 1177 phosphorylation in response to hyperglycemia. In contrast, when myc-tagged human eNOS carried a mutation at the Akt phosphorylation site (Ser1177), O-linked N-acetylglucosamine modification was unchanged by hyperglycemia and phospho-eNOS was undetectable. Similar changes in eNOS activity and covalent modification were found in aortae from diabetic animals. Chronic impairment of eNOS activity by this mechanism may partly explain the accelerated atherosclerosis of diabetes.
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PMID:Hyperglycemia inhibits endothelial nitric oxide synthase activity by posttranslational modification at the Akt site. 1171 33


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