Characteristic distribution of sulfated mucopolysaccharides in different tissues and in their respective mitochondria

Intercellular Glycosaminoglycans in Human Cancer

Intercellular glycosaminoglycans (GAGs) from various tissues were analyzed by cellulose acetate electrophoresis and enzymatic treatment with specific mucopolysaccharidases. Each tissue exhibits a particular composition of sulfated and unsulfated molecular species. Invariably, malignant human neoplasias and their metastases show striking variations in the electrophoretic pattern typical of the corresponding normal tissue. An absolute or relative increase in surface ChS A/C and HA seems to be a consistent feature of neoplastic transformation. On the other hand, the GAGs composition of benign noninfiltrative tumors does not vary greatly with respect to the original normal tissue.

A novel fibroblast growth factor-1 ligand with reduced heparin binding protects the heart against ischemia-reperfusion injury in the presence of heparin co-administration

AIMS

Fibroblast growth factor 1 (FGF1), a heparin/heparan sulfate-binding growth factor, is a potent cardioprotective agent against myocardial infarction (MI). The impact of heparin, the standard of care for MI patients entering the emergency room, on cardioprotective effects of FGF1 is unknown, however.

METHODS AND RESULTS

To address this, a rat model of MI was employed to compare cardioprotective potentials (lower infarct size and improve post-ischemic function) of native FGF1 and an engineered FGF1 (FGF1ΔHBS) with reduced heparin-binding affinity when given at the onset of reperfusion in the absence or presence of heparin. FGF1 and FGF1ΔHBS did not alter heparin's anticoagulant properties. Treatment with heparin alone or native FGF1 significantly reduced infarct size compared to saline (P < 0.05). Surprisingly, treatment with FGF1ΔHBS markedly lowered infarct size compared to FGF1 (P < 0.05). Both native and modified FGF1 restored contractile and relaxation function (P < 0.05 versus saline or heparin). Furthermore, FGF1ΔHBS had greater improvement in cardiac function compared to FGF1 (P < 0.05). Heparin negatively impacted the cardioprotective effects (infarct size, post-ischemic recovery of function) of FGF1 (P < 0.05) but not of FGF1ΔHBS. Heparin also reduced the biodistribution of FGF1, but not FGF1ΔHBS, to the left ventricle. FGF1 and FGF1ΔHBS bound and triggered FGFR1-induced downstream activation of ERK1/2 (P < 0.05); yet, heparin co-treatment decreased FGF1-produced ERK1/2 activation, but not that activated by FGF1ΔHBS.

CONCLUSION

These findings demonstrate that modification of the heparin-binding region of FGF1 significantly improves the cardioprotective efficacy, even in the presence of heparin, identifying a novel FGF ligand available for therapeutic use in ischemic heart disease.

A structural analysis of glycosaminoglycans from lethal and nonlethal breast cancer tissues: toward a novel class of theragnostics for personalized medicine in oncology?

Cancer is one of the leading noncommunicable diseases that vastly impacts both developed and developing countries. Truly innovative diagnostics that inform disease susceptibility, prognosis, and/or response to treatment (theragnostics) are seriously needed for global public health and personalized medicine for patients with cancer. This study examined the structure and content of glycosaminoglycans (GAGs) in lethal and nonlethal breast cancer tissues from six patients. The glycosaminoglycan content isolated from tissue containing lethal cancer tumors was approximately twice that of other tissues. Molecular weight analysis showed that glycosaminoglycans from cancerous tissue had a longer weight average chain length by an average of five disaccharide units, an increase of approximately 15%. Dissacharide analysis found differences in sulfation patterns between cancerous and normal tissues, as well as sulfation differences in GAG chains isolated from patients with lethal and nonlethal cancer. Specifically, cancerous tissue showed an increase in sulfation at the "6S" position of CS chains and an increase in the levels of the HS disaccharide NSCS. Patients with lethal cancer showed a decrease in HS sulfation, with lower levels of "6S" and higher levels of the unsulfated "0S" disaccharide. Although these findings come from a limited sample size, they indicate that structural changes in GAGs exist between cancerous and noncancerous tissues and between tissues from patients with highly metastatic cancer and cancer that was successfully treated by chemotherapy. Based on these findings, we hypothesize that (1) there are putative changes in the body's construction of GAGs as tissue becomes cancerous; (2) there may be innate structural person-to-person variations in GAG composition that facilitate the metastasis of tumors in some patients when they develop cancer.

Urinary glycosaminoglycans excretion and the effect of dimethyl sulfoxide in an experimental model of non-bacterial cystitis

PURPOSE

We reproduced a non-bacterial experimental model to assess bladder inflammation and urinary glycosaminoglycans (GAG) excretion and examined the effect of dimethyl sulfoxide (DMSO).

MATERIALS AND METHODS

Female rats were instilled with either protamine sulfate (PS groups) or sterile saline (control groups). At different days after the procedure, 24 h urine and bladder samples were obtained. Urinary levels of hyaluronic acid (HA) and sulfated glycosaminoglycans (S-GAG) were determined. Also to evaluate the effect of DMSO animals were instilled with either 50% DMSO or saline 6 hours after PS instillation. To evaluate the effect of DMSO in healthy bladders, rats were instilled with 50% DMSO and controls with saline.

RESULTS

In the PS groups, bladder inflammation was observed, with polymorphonuclear cells during the first days and lymphomononuclear in the last days. HA and S-GAG had 2 peaks of urinary excretion, at the 1st and 7th day after PS injection. DMSO significantly reduced bladder inflammation. In contrast, in healthy bladders, DMSO produced mild inflammation and an increase in urinary HA levels after 1 and 7 days and an increase of S-GAG level in 7 days. Animals instilled with PS and treated with DMSO had significantly reduced levels of urinary HA only at the 1st day. Urinary S-GAG/Cr levels were similar in all groups.

CONCLUSIONS

Increased urinary levels of GAG were associated with bladder inflammation in a PS-induced cystitis model. DMSO significantly reduced the inflammatory process after urothelial injury. Conversely, this drug provoked mild inflammation in normal mucosa. DMSO treatment was shown to influence urinary HA excretion.

Acidic amino acid tag enhances response to enzyme replacement in mucopolysaccharidosis type VII mice

We have tested an acidic oligopeptide-based targeting system for delivery of enzymes to tissues, especially bone and brain, in a murine mucopolysaccharidosis type VII (MPS VII) model. This strategy is based upon tagging a short peptide consisting of acidic amino acids (AAA) to N terminus of human beta-glucuronidase (GUS). The pharmacokinetics, biodistribution, and the pathological effect on MPS VII mouse after 12 weekly infusions were determined for recombinant human untagged and tagged GUS. The tagged GUS was taken up by MPS VII fibroblasts in a mannose 6-phosphate receptor-dependent manner. Intravenously injected AAA-tagged enzyme had five times more prolonged blood clearance compared with the untagged enzyme. The tagged enzyme was delivered effectively to bone, bone marrow, and brain in MPS VII mice and was effective in reversing the storage pathology. The storage in osteoblasts was cleared similarly with both enzyme types. However, cartilage showed a little response to any of the enzymes. The tagged enzyme reduced storage in cortical neurons, hippocampus, and glia cells. A highly sensitive method of tandem mass spectrometry on serum indicated that the concentration of serum dermatan sulfate and heparan sulfate in mice treated with the tagged enzyme decreased more than the untagged enzyme. These preclinical studies suggest that this AAA-based targeting system may enhance enzyme-replacement therapy.

Nonheme iron absorption in young women is not influenced by purified sulfated and unsulfated glycosaminoglycans

Meat is a well-known enhancer of iron absorption, yet the molecular entity mediating the effect remains obscure. Recently published data indicate that highly acidic sulfated glycosaminoglycans (GAG) from fish and chicken muscle are effective stimulants of iron uptake in Caco-2 cells. Two fully randomized stable isotope studies with crossover design were performed in a group of 16 apparently healthy young women to assess the effect of purified sulfated and unsulfated GAG on human iron absorption. Iron absorption was measured on the basis of erythrocyte incorporation of (57)Fe or (58)Fe 14 d after the administration of labeled semisynthetic meals (SSM) based on egg albumin, corn oil, maltodextrin, and water. The meals were consumed with or without added sodium hyaluronate (NaH, 300 mg) or chondroitin sulfate (CS, 360 mg) as representative unsulfated and sulfated GAG, respectively. The level of GAG added was 3 times (NaH) to about 10 times (CS), the amount expected to be present in 150 g beef muscle. Geometric mean iron absorption from SSM containing NaH (21.2%) or CS (19.4%) did not differ from that of SSM without GAG (19.5 and 20.3%, respectively). NaH and CS at those levels do not affect human nonheme iron absorption.

GLICOSIDASES E SULFATASES NO MOLUSCO MARINHO APLYSIA CERVINA

RESUMO Glicosaminoglicanos (GAGs) são carboidratos presentes em todos os organismos que apresentam organização tissular. Glicosidases e sulfatases são as enzimas envolvidas na degradação destes compostos em vertebrados e invertebrados. O objetivo deste trabalho foi identificar a presença destas enzimas em diferentes tecidos do molusco Aplysiacervina. O molusco foi dissecado em esôfago, fígado, moela e músculo e homogeneizados separadamente. Após centrifugação os sobrenadantes (extratos brutos) foram fracionados com sulfato de amônio nas concentrações de 0-30% (F-I), 30-50% (FII) e 50-80% (FIII). Foi identificada a presença de sulfatase, β-glucuronidase, β-D-N-acetilgalactosaminidase e α-glucosaminidase nos extratos brutos de todos os tecidos investigados. A enzima α-fucosidase não foi detectada em esôfago, nos extratos brutos e F-I de moela, mas sim nas frações de fígado e músculo. A sulfatase apresentou-se mais ativa na F-III de fígado e moela com atividades específicas de 3,0 e 4,8, respectivamente. A α-glucosaminidase foi mais ativa nas frações F-III de esôfago e músculo apresentando atividades específicas de 3,9 e 2,0, respectivamente. Estes resultados indicam a existência de atividade catabólica sobre os GAGs neste invertebrado marinho.

Changes in cat urinary glycosaminoglycans with age and in feline urologic syndrome

The aim of the present study was to characterize the urinary excretion of glycosaminoglycans in kittens and adult healthy cats, as well as in cats with a low urinary tract disease, the feline urologic syndrome (FUS). The main urinary glycosaminoglycan in cats was found to be chondroitin sulfate, with smaller amounts of dermatan sulfate and heparan sulfate. There was no difference in the urinary glycosaminoglycan concentration with sex, but a marked decrease occurred with age, due to chondroitin sulfate. Trace amounts of keratan sulfate were also detected in the urine of kittens, but not of healthy adult cats. Dermatan sulfate and heparan sulfate were the only glycosaminoglycans found in the urinary tract and kidney, and chondroitin sulfate was the only glycosaminoglycan found in the plasma. These data suggest that the main urinary glycosaminoglycan chondroitin sulfate is of systemic origin and filtered in the kidney, while the minor components dermatan sulfate and heparan sulfate may come from the urinary tract. The urinary glycosaminoglycan concentration was greatly decreased in animals with FUS, as compared to normal adults. We hypothesize that these low glycosaminoglycan levels reflect a damage to the bladder surface, resulting in absorption and/or degradation of the endogenous urinary glycosaminoglycans.

Alterations in Granule Matrix and Cell Surface of Focal Adhesion Kinase-Deficient Mast Cells

Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase that plays an important role in many cellular processes and is tyrosine phosphorylated after FcepsilonRI aggregation in mast cells. In mice, null mutation of the fak gene results in a lethal phenotype in which the embryos fail to develop past day 8.5 of gestation. To study the role of FAK in these mast cells, 8.5-day embryos were isolated and placed in culture with IL-3 and stem cell factor (SCF). Although FAK was not required for the development of mast cells in culture, the FAK(-/-) embryo-derived mast cells had several distinct characteristics. Compared with the controls, the mast cells that lack FAK were less metachromatic and by electron microscopy had granules that appeared largely electron lucid, although their histamine content was unchanged. The FAK-deficient mast cells had a reduction in the content of chondroitin/dermatan sulfate, the major glycosaminoglycan component of the granular matrix. The FAK-deficient cells had fewer microvilli that were fused with each other, giving the cell surface a ruffled appearance. There was also a 3-fold increase in the number of cells highly expressing beta(7) integrin. However, signal transduction from the high affinity IgE receptor for the secretion of histamine was similar in the wild-type, heterozygote, and the FAK-deficient cells. The FcepsilonRI-induced tyrosine phosphorylation of paxillin, Crk-associated tyrosine kinase substrate (CAS), and mitogen-activated protein kinase proteins was independent of FAK. These results indicate that FAK plays a role in regulating the glycosaminoglycan content of the secretory granules and influences the cell surface morphology of mast cells.

Inhibition of heparin synthesis by methotrexate in rats in vivo

The content and synthesis of heparin and mast cell-dependent skin oedema (as an indirect evaluation of histamine and serotonin content) were investigated in the rat skin after chronic treatment with compound 48/80, a mast cell degranulating substance. The effect of methotrexate, a folic acid analogue that interrupts the synthesis of DNA and RNA, on heparin synthesis and amine storage also was evaluated in rat skin. The heparin content at 6 and 240 hr after treatment with compound 48/80 was reduced markedly (86 and 64%, respectively). At 6 hr, heparin synthesis increased 3.1-fold compared with control animals; maximal synthesis occurred at 24 hr post-treatment (12.8-fold increase), decaying at 240 hr (2.4-fold increase). The dermatan sulfate content and synthesis were not affected by treatment with compound 48/80. Autoradiographic analysis revealed that methotrexate (2.5mg/kg for 3 consecutive days) abolished heparin synthesis at 6, 24, and 72 hr after compound 48/80 treatment, without affecting dermatan sulfate synthesis. The oedema induced by intradermal injection of compound 48/80 (1 microg/site) into the rat skin was decreased significantly at 6 hr after chronic treatment with this compound, but was restored completely 72 hr post-treatment. This pattern of oedematogenic response was also observed in the methotrexate-treated rats. In conclusion, our results show that methotrexate suppresses heparin synthesis without affecting the synthesis of either dermatan sulfate or the co-stored amines histamine/serotonin (as evaluated by measuring the mast cell-dependent oedema), suggesting that the enzyme system involved in heparin synthesis is inducible.

A fucan from the brown seaweed Spatoglossum schröederi inhibits Chinese hamster ovary cell adhesion to several extracellular matrix proteins

Fucans, a family of sulfated polysaccharides present in brown seaweed, have several biological activities. Their use as drugs would offer the advantage of no potential risk of contamination with viruses or particles such as prions. A fucan prepared from Spatoglossum schröederi was tested as a possible inhibitor of cell-matrix interactions using wild-type Chinese hamster ovary cells (CHO-K1) and the mutant type deficient in xylosyltransferase (CHO-745). The effect of this polymer on adhesion properties with specific extracellular matrix components was studied using several matrix proteins as substrates for cell attachment. Treatment with the polymer inhibited the adhesion of fibronectin to both CHO-K1 (2 x 10(5)) and CHO-745 (2 x 10(5) and 5 x 10(5)) cells. No effect was detected with laminin, using the two cell types. On the other hand, adhesion to vitronectin was inhibited in CHO-K1 cells and adhesion to type I collagen was inhibited in CHO-745 cells. In spite of this inhibition, the fucan did not affect either cell proliferation or cell cycle. These results demonstrate that this polymer is a new anti-adhesive compound with potential pharmacological applications.

Neurotrophin stimulation of human melanoma cell invasion: selected enhancement of heparanase activity and heparanase degradation of specific heparan sulfate subpopulations

Heparanase is an endo-beta-D-glucuronidase whose enzymatic targets are the glycosaminoglycan chains of heparan sulfate proteoglycans (50). Elevated levels of heparanase are associated with the metastatic potential of melanoma cells, and treatment of murine and human melanoma cells with the prototypic neurotrophin nerve growth factor (NGF) increases the production of heparanase by melanoma cells. We previously reported that physiological concentrations of NGF increased invasion of early passage human brain-metastatic 70W melanoma cells but not melanoma cells metastatic to other sites or nonmetastatic melanoma cells as measured in Matrigel invasion assays. Here we found that treatment of 70W melanoma cells with neurotrophin-3 (NT-3) increased Matrigel invasion, whereas treatment with neurotrophins other than NGF or NT-3 did not influence invasion. Mutants of NGF that do not bind to the neurotrophin receptor p75NTR or other nonneuronal growth factors were not able to enhance the invasion of 70W melanoma cells. When 70W cells were exposed to antisense oligonucleotides directed against p75NTR mRNA, there was a reduction in NGF and NT-3 binding, and the neurotrophins failed to enhance Matrigel invasion. To study the properties of heparanase in neurotrophin-regulated malignant melanoma invasive processes, we developed a sensitive heparanase assay consisting of purified [35S]HS subpopulations separated by agarose gel electrophoresis. Incubation of 70W cells with NGF or NT-3 but not brain-derived neurotrophic factor, neurotrophin-4/5 or mutant NGF resulted in increased release of heparanase activity that was capable of degrading a subpopulation of heparan sulfate molecules.

Age-related changes in glycosaminoglycan distribution in different anatomical sites on the surface of knee-joint articular cartilage in young rabbits

In spite of the fact that the various anatomical regions of a given articular cartilage surface are subjected to different degrees of stress, the present observations strongly suggest that there exists a topographical homogeneity in the distribution of glycosaminoglycans in the same articular cartilage. In contrast to this age-related changes in the proportion of the different types of glycosaminoglycan species in articular cartilage are remarkable. Non-sulphated chondroitin could only be detected in very young articular cartilage. Dermatan sulphate, which has already been detected in young adult rabbits, was followed by the appearance of keratan sulphate in older rabbits. Chondroitin 4-6-sulphates were detected in all articular cartilages studied, the proportion of the 6-sulphated variably increasing with age. The present report suggests that the distribution of glycosaminoglycans in articular cartilage varies with species and age, and the data can further vary, depending on the methods used. It is therefore concluded that generalizations against the results reported in the literature should be considered skeptically.

Proteoglycan synthesis by clonal skeletal muscle cells during in vitro myogenesis: differences detected in the types and patterns from primary cultures

Proteoglycan synthesis by two clonal murine skeletal muscle cell lines, G8-1 and C2, was examined. Cultures of skeletal muscle cells at both the myoblast and myotube stages were radiolabeled using [35S]sulfate as a precursor. The proteoglycans of the cell layer and medium were separately extracted and isolated by ion exchange chromatography on DEAE-Sephacel followed by gel filtration chromatography on Sepharose CL-2B. The cell layer proteoglycans eluted from Sepharose CL-20 as a single peak with a Kav of 0.66 and contained glycosaminoglycan chains with an average molecular weight of 20,000. The glycosaminoglycan chains were composed of nearly equal mixtures of chondroitin sulfate and heparan sulfate with the exception that C2 myoblast cultures contained larger amounts of heparan sulfate. Of interest, this line differentiates more rapidly in our laboratory than G8-1. The medium proteoglycans also eluted from Sepharose CL-2B as a single peak with a Kav of 0.66 but contained glycosaminoglycan chains with an average molecular weight of 32,000. Based upon enzymatic and chemical analysis, the medium glycosaminoglycan chains were composed of a mixture of chondroitin sulfate (71-80%) and heparin sulfate (19-22%). Following chondroitinase ABC digestion, the predominant disaccharide released from all glycosaminoglycan fractions was chondroitin-4-sulfate. When the extracted cell layer proteoglycans were chromatographed on Sepharose CL-28 in the absence of detergent, a small but consistent proportion (14-18%) eluted in the void volume, suggesting the association of at least a portion of this proteoglycan with cellular lipid. These differences distinguish proteoglycan metabolism in fusing clonal lines from primary muscle cell cultures suggesting their utility in evaluating the contribution of these macromolecules in myogenesis.

Proteoglycans in the pathogenesis of Alzheimer's disease and other amyloidoses

Proteoglycans and the amyloid P component are two constituents of amyloid that appear to be present regardless of the type of amyloid protein deposited, the extent of amyloid deposition and the tissue or organ involved. This article reviews the literature concerning proteoglycans and/or glycosaminoglycans in amyloidosis and describes recent studies which demonstrate their localization to the characteristic lesions of Alzheimer's disease and the amyloid plaques containing PrP protein in the prion diseases. Additionally, the possible interaction of proteoglycans with various amyloidogenic proteins, including the beta-amyloid protein in Alzheimer's disease is discussed. It is postulated that proteoglycans localized to a number of different amyloids play a common role in the pathogenesis of amyloidosis. Some of these hypothesized roles include 1) inducing amyloidogenic precursor proteins to form amyloid fibrils containing a predominant beta-pleated sheet structure, 2) influencing amyloid deposition to occur at specific anatomical sites within tissues and/or 3) aiding in prevention of amyloid degradation once amyloid has formed.

Proteoglycan synthesis by primary chick skeletal muscle during in vitro myogenesis

The proteoglycans synthesized by primary chick skeletal muscle during in vitro myogenesis were compared with those of muscle-specific fibroblasts. Cultures of skeletal muscle cells and muscle fibroblasts were separately labeled using [35S] sulfate as a precursor. The proteoglycans of the cell layer and medium were separately extracted and isolated by ion-exchange chromatography on DEAE-Sephacel followed by gel filtration chromatography on Sepharose CL-2B. Two cell layer-associated proteoglycans synthesized both by skeletal muscle cells and muscle fibroblasts were identified. The first, a high molecular weight proteoglycan, eluted from Sepharose CL-2B with a Kav of 0.07 and contained exclusively chondroitin sulfate chains with an average molecular weight greater than 50,000. The second, a relatively smaller proteoglycan, eluted from Sepharose CL-2B with a Kav of 0.61 and contained primarily heparan sulfate chains with an average molecular weight of 16,000. Two labeled proteoglycans were also found in the medium of both skeletal muscle and muscle fibroblasts. A high molecular weight proteoglycan was found with virtually identical properties to that of the high molecular weight chondroitin sulfate proteoglycan of the cell layer. A second, smaller proteoglycan had a similar monomer size (Kav of 0.63) to the cell layer heparan sulfate proteoglycan, but differed from it in that this molecule contained primarily chondroitin sulfate chains with an average molecular weight of 32,000. Studies on the distribution of these proteoglycans in muscle cells during in vitro myogenesis demonstrated that a parallel increase in the relative amounts of the smaller proteoglycans occurred in both the cell layer and medium compared to the large chondroitin sulfate proteoglycan in each compartment. In contrast, muscle-derived fibroblasts displayed a constant ratio of the small proteoglycans of the cell layer and medium fractions, compared to the larger chondroitin sulfate proteoglycan of the respective fraction as a function of cell density. Our results support the concept that proteoglycan synthesis is under developmental regulation during skeletal myogenesis.

Mucopolysaccharidases from Pseudomonas sp. Isolation and partial characterization of constitutive enzymes involved in the degradation of keratan sulfate and chondroitin sulfate

Four constitutive enzymes, capable of degrading keratan sulfate, were isolated from Pseudomonas sp.: a particulate endoglycosidase, a soluble endoglycosidase, a soluble exo-beta-D-galactosidase and a soluble exo-beta-D-N-acetylglucosaminidase. The endoglycosidases were shown to act only upon keratan sulfate forming beta-D-2-acetamido-2-deoxy-6-O-sulfoglucosyl-(1----3)-D-galactose, as the main product. This results indicates that the enzyme catalyses the hydrolysis of beta-D-galactose-(1----4)-N-acetylglucosamine linkages. It was also shown that this monosulfated disaccharide inhibits the particulate keratan sulfate endoglycosidase. The bovine nucleus pulposus keratan sulfate is depolymerized at a lower rate and extent when compared to the corneal keratan sulfate. The soluble endoglycosidase is very labile, in contrast to the particulate enzyme, which has been stored at -20 degrees C or at 4 degrees C for at least 12 months with no loss in activity. The particulate endoglycosidase and the soluble exo-beta-D-galactosidase and exo-beta-D-N-acetylglucosaminidase are induced when the bacteria is grown in adaptative media containing either 0.1% keratan sulfate or 0.1% chondroitin sulfate. Furthermore, particulate forms of the exoenzymes were detected. The soluble endoglycosidase specific activity, in contrast, is approximately the same in extracts of cells grown in glucose, keratan sulfate or chondroitin sulfate. A chondroitin sulfate lyase was also identified in the soluble extracts of Pseudomonas sp. cells. This enzyme depolymerizes chondroitin 4-sulfate, chondroitin 6-sulfate and hyaluronic acid forming unsaturated disaccharides as main products. It is also active upon the glucuronic-acid-containing regions of the dermatan sulfate molecules. The properties of the soluble enzymes, further purified by ion-exchange chromatography, and of the particulate keratan sulfate endoglycosidase are presented.

Sulphation and the vegetative growth of Dictyostelium discoideum

The utilization of [35S]sulphate by bacterially grown amoebae of Dictyostelium discoideum strain NP73 was examined in this study. During vegetative growth the sulphation of at least ten macromolecules was observed. These macromolecules had molecular masses less than 66 kDa and isoelectric points below 5. Simple tests indicated that the sulphate linkage was periodate-sensitive but not acid-labile which implied that carbohydrate moieties, rather than tyrosine residues, were sulphated. Pulse-chase experiments indicated that the sulphated macromolecules were extremely stable during vegetative growth, but that secretion occurred on starvation, resulting in the loss of the sulphated macromolecules to the extracellular medium. Incorporation of [35S]sulphate into these macromolecules by amoebae declined rapidly within 2 h of starvation on membrane filters. In contrast, incorporation by amoebae starving in suspension culture continued for 6-8 h. Similar patterns of [35S]sulphate incorporation were observed for two other strains of D. discoideum (strains AX2 and NC4) and for Polysphondylium violaceum. Since in a previous study it was shown that the sulphation inhibitor, sodium selenate, arrests the growth of D. discoideum [Davis, S.J. & Wheldrake, J.F. (1985) FEMS Micro Lett. 30, 353-358], it is suggested that the sulphation of these macromolecules is necessary for the vegetative growth of D. discoideum.

Developmental changes of proteoglycan synthesis in rat liver and isolated hepatocytes

The synthesis of sulfated proteoglycans in late fetal (19th to 22nd day of intrauterine life), early postnatal, and adult liver tissue as well as in hepatocytes and their distribution in plasma membranes were studied. Overall proteoglycan production is enhanced two-fold in fetal as compared with adult liver tissue. In contrast to slices from adult liver, in which the synthesis of heparan [35S]-sulfate comprises more than 80% and chondroitin sulfate less than 5% of total glycosaminoglycans, chondroitin [35S]sulfate is the major type of glycosaminoglycans synthesized in fetal liver representing about 50% of total sulfated glycosaminoglycans. Thus, the synthesis of chondroitin sulfate is elevated nearly 30-fold in fetal liver as compared with the adult counterpart. Immediately after birth chondroitin sulfate formation decreases rapidly reaching adult levels between the 10th and 15th day of postnatal life. The production of heparan sulfate is almost unchanged during perinatal liver development due to a relatively low fractional synthesis of heparan [35S]sulfate in fetal liver. Hepatocytes were identified as the cell type responsible for elevated chondroitin sulfate production in fetal liver. Erythroblasts, which synthesize chondroitin sulfate, contribute less than 10% to total glycosaminoglycan synthesis in embryonic liver. Plasma membranes of adult liver contain exclusively heparan sulfate whereas in neonatal liver cell membranes 25% of labeled glycosaminoglycans is represented by chondroitin sulfate, a fraction which decreases rapidly after birth. In parallel to the postnatal shut down of chondroitin sulfate synthesis the activity of the UDPxylose:coreprotein xylosyltransferase (EC. 2.4.2.26) decreases from 4.8 +/- 0.5 dpm/h per microgram protein to 0.3 +/- 0.1 dpm/h per microgram protein suggesting a regulatory function of the enzyme for proteochondroitin sulfate synthesis in developing liver. The formation of both heparan sulfate and chondroitin sulfate is dependent on functioning protein synthesis, which indicates, together with double labeling experiments using [3H]serine and [14C]glucosamine as isotopic precursors, their synthesis as proteoglycans. The positive correlation (r = 0.949) between the incorporation of [3H]thymidine into DNA and chondroitin [35S]sulfate production supports the assumption of a cell growth promoting activity of chondroitin sulfate and points to a significant role of the glycosaminoglycan in the process of cellular proliferation and tissue differentiation.

Chemically induced renal papillary necrosis and upper urothelial carcinoma. Part 1

In the past, renal papillary necrosis (RPN) has been commonly associated with long-term abusive analgesic intake, but over recent years a wide variety of industrially and therapeutically used chemicals have been shown to induce this lesion experimentally or in man. Destruction of the renal papilla may result in: (1) secondary degenerative cortical changes which precede chronic renal failure or (2) a rapidly metastasizing upper urothelial carcinoma, which has a very poor prognosis. This article will briefly review the published data on the morphology, function, and biochemistry of the normal renal medulla and the pathology associated with RPN, together with the secondary changes which give rise to cortical degeneration or epithelial carcinoma. It will then examine in detail those chemicals which have been reported to cause RPN in an attempt to delineate structure-activity relationships. Finally, the many different theories that have been proposed to explain the pathophysiology of RPN will be examined and an hypothesis will be put forward to explain the primary pathogenesis of the lesion and its secondary consequences.

Chemically induced renal papillary necrosis and upper urothelial carcinoma. Part 2

In the past, renal papillary necrosis (RPN) has been commonly associated with long-term abusive analgesic intake, but over recent years a wide variety of industrially and therapeutically used chemicals have been shown to induce this lesion experimentally or in man. Destruction of the renal papilla may result in: (1) secondary degenerative cortical changes which precede chronic renal failure or (2) a rapidly metastasizing upper urothelial carcinoma, which has a very poor prognosis. This article will briefly review the published data on the morphology, function, and biochemistry of the normal renal medulla and the pathology associated with RPN, together with the secondary changes which give rise to cortical degeneration or epithelial carcinoma. It will then examine in detail those chemicals which have been reported to cause RPN in an attempt to delineate structure-activity relationships. Finally, the many different theories that have been proposed to explain the pathophysiology of RPN will be examined and an hypothesis will be put forward to explain the primary pathogenesis of the lesion and its secondary consequences.

Anticoagulant properties in vitro of heparan sulphates

The anticoagulant properties in vitro of eight heparan sulphate preparations were studied using clotting (APTT, anti-Xa) and amidolytic (anti-Xa, anti-thrombin) assays. Activities ranged from very low levels (less than 5 iu/mg) up to values similar to those of heparin. Activities measured by APTT assay showed the best correlation with the sulphate to carboxylate ratio of the heparan sulphates. Highest activities were obtained in the anti-Xa clotting assay, these being approximately two-fold greater than activities in the anti-Xa amidolytic assay. Five of the heparan sulphate preparations were readily neutralised by protamine sulphate, whereas the three heparans with the lowest sulphate to carboxylate ratio were much more resistant to neutralisation. After fractionating each heparan sulphate into At III-binding and non-binding material, it was found that the anti-coagulant properties were associated only with the former. It is concluded that these properties are dependent on the activation of At III.

An inverse relationship between heparin content and antibody response in genetically selected mice. Sex effect and evidence of a polygenic control for skin heparin concentration

The heparin content of genetically selected mice with high and low antibody response to bacterial antigens is reported. An inverse relationship between antibody titres and concentration of heparin was observed for both male and female mice. The lower-antibody-responder line contains twice as much heparin as the higher-responder ones. Furthermore, the female mice also contained twice as much heparin as the male mice. Genetic analysis of the parental and interline hybrids has shown a partial dominance for the character 'heparin content' in favour of the high-heparin phenotype and this character appears to be subjected to polygenic control. The possible biological role of heparin and/or mast cells in the surveillance of the organism against some pathogens is discussed in the light of these and other findings.

Disulfide-bonded aggregates of heparan sulfate proteoglycans

Heparan sulfate proteoglycans have been isolated from Swiss mouse 3T3 cells by using two nondegradative techniques: extraction with 4 M guanidine or 2.5% 1-butanol. These proteoglycans were separated from copurifying chondroitin sulfate proteoglycans by using ion-exchange chromatography on DEAE-cellulose in the presence of 2 M urea. The purified heparan sulfate proteoglycans are substantially smaller, ca. Mr 20 000, than those isolated from these same cells with trypsin, ca. Mr 720 000 [Johnston, L.S., Keller, K. L., & Keller, J. M. (1979) Biochim. Biophys. Acta 583, 81-94]. However, all of the heparan sulfate proteoglycans extracted by these three methods contain similar glycosaminoglycan chains (Mr 7500) and are derived from the same pool of cell surface associated molecules. The trypsin-released heparan sulfate proteoglycan (ca. Mr 720 000) can be significantly reduced in size (ca. Mr 33 000) under strong denaturing conditions in the presence of the disulfide reducing agent dithiothreitol, which suggests that this form of the molecule is a disulfide-bonded aggregate. The heparan sulfate proteoglycan isolated from the medium also undergoes a significant size reduction in the presence of dithiothreitol, indicating that a similar aggregate is formed as part of the normal release of heparan sulfate proteoglycans into the medium. These results suggest that well-shielded disulfide bonds between individual heparan sulfate proteoglycan monomers may account for the large variation in sizes which has been reported for heparan sulfate proteoglycans isolated from a variety of cells and tissues with a variety of extraction procedures.

Mapping by monoclonal antibody detection of glycosaminoglycans in connective tissues

Chondroitin sulphate proteoglycans are widespread connective tissue components and chemical analysis of cartilage and other proteoglycans has demonstrated molecular speciation involving the degree and position of sulphation of the carbohydrate chains. This may, in turn, affect the properties of the glycosaminoglycan (GAG), particularly with respect to self-association and interactions with other extracellular matrix components. Interactions with specific molecules from different connective tissue types, such as the collagens and their associated glycoproteins, could be favoured by particular charge organizations on the GAG molecule endowed by the sulphate groups. So far, it has not been possible to identify and map chondroitins of differing sulphation in tissues, but we have now raised three monoclonal antibodies which specifically recognize unsulphated, 4-sulphated and 6-sulphated chondroitin and dermatan sulphate. These provide novel opportunities to study the in vivo distribution of chondroitin sulphate proteoglycans. We demonstrate that chondroitin sulphates exhibit remarkable connective tissue specificity and furthermore provide evidence that some proteoglycans may predominantly carry only one type of chondroitin sulphate chain.

Inhibition of rat salivary gland adenylate cyclase by glycosaminoglycans and high molecular weight polyanions

The effects of hyaluronic acid, chondroitin-4 and -6 sulphate, dermatan sulphate, heparin and the sulphated, polysugar dextran sulphate on membrane-associated adenylate cyclase were investigated in a plasma-membrane fraction derived from the glands. Adenylate-cyclase activity was inhibited in a dose-dependent fashion by all. The potency (concentration causing a 50 per cent inhibition (Ki) of adenylate cyclase activity) of each molecule varied with the degree of sulphation of the agent tested. The GTP and Gpp(NH)p activation of adenylate cyclase as well as basal-enzyme activity and of adenylate cyclase by isoproterenol (a beta-adrenergic agonist) were inhibited; however, little effect on hormone binding (assessed by [3H]-dihydroalprenolol binding) was observed at Ki concentrations. Inhibition of NaF-activation of adenylate cyclase was not as pronounced as the other inhibitory effects. The findings suggested that the agents inhibited enzyme activity by action at or near the catalytic site; hence the effect of these molecules on forskolin activation of adenylate cyclase was investigated. The polyanions inhibited forskolin stimulation of the enzyme to the same degree that they had previously inhibited basal, GTP and hormonally-stimulated enzyme activity. Thus, these molecules inhibited adenylate cyclase by an action (perhaps charge-related) that directly effected the stabilization of catalytic site of the enzyme. Thus polyanions of the type tested can directly modulate adenylate-cyclase activity and may serve as potential regulatory molecules for various biologic functions which are cyclic-AMP dependent.

Characterization of polysaccharides of the eggs and adults of Hymenolepis diminuta

Polysaccharides and other complex carbohydrates were released by proteolysis of the chloroform-methanol insoluble residue of 10 day-old worms and eggs of Hymenolepis diminuta. Gas-liquid chromatographic analysis of alditol acetate derivatives of monosaccharides released from the polysaccharides by hydrolysis revealed that in the 10 day-old worm, glucose was the most abundant sugar, followed by galactose, glucosamine, galactosamine, fucose and possibly rhamnose. Mannose was least abundant and xylose was absent. In the egg, glucose and galactose were equally abundant, followed by the same sugars found in 10 day-old worms, and xylose was present. Uronic acid was detected in both fractions by specific chemical tests. None of the saccharide material from eggs and worms was susceptible to degradation by Streptomyces hyaluronidase, chondroitinase AC, and slightly susceptible to chondroitinase ABC, as shown by electrophoretic analysis on composite 2.2% acrylamide-agarose slab gels and 4.5/12.5% polyacrylamide gels before and after enzymatic treatment. One of the gel-separable bands, however, was degradable by both nitrous acid and Flavobacterium heparinase. Both bands from eggs were degradable by nitrous acid. These results suggest that eggs contain heparin and/or heparan sulfate and perhaps dermatan sulfate and that 10 day-old worms also have these polyglycans but possibly not chondroitin sulfate or hyaluronic acid.

Influences of anionic polysaccharides on DNA synthesis in isolated nuclei and by DNA polymerase alpha: correlation of observed effects with properties of the polysaccharides

The basis of the differential effect of anionic polysaccharides on replicative DNA synthesis in liver and hepatoma cell nuclei was investigated. The differential effect of heparin was lost when more than 40% of its sulfate was removed. DNA synthesis in liver nuclei was optimally stimulated by heparin of molecular weight 22600 and sulfate to hexosamine ratio 2.42, but inhibited by heparin of molecular weight 4300 and sulfate to hexosamine ratio 2.35. A heparin fragment (molecular weight 2800 and sulfate to hexosamine ratio 1.81), prepared by partial nitrous acid treatment was a potent inhibitor of DNA synthesis in hepatoma nuclei. There was no significant difference in the rate of entry of heparin or its subfractions into either liver or hepatoma nuclei. In both cases less than 15% of added polysaccharide entered the nuclei and only about 4.5% was found associated with the chromatin. The influence of the anionic polysaccharides on DNA synthesis was correlated with their ability to complex with histones as determined by relative light scattering in a laser nephelometer. The relative light scattered on mixing with histones (H1, H2A + H3, H4) was high for DNA synthesis stimulators (heparin, dextran sulfate); medium for DNA synthesis inhibitors (chondroitin 4- and 6-sulfates, heparan sulfate) and low for non-effectors (keratan sulfate, hyaluronic acid). Heparin and chondroitin sulfate H, which at low concentrations stimulate DNA synthesis in liver nuclei, inhibited DNA synthesis by calf thymus DNA polymerase alpha at all concentrations. This inhibition was not simply due to electrostatic interactions.

Laser nephelometric determination of glycosaminoglycans--method and application

Light scattering due to the formation of insoluble complexes between the long-chain quaternary ammonium salt N-cetylpyridinium chloride and glycosaminoglycans was utilized for a relative simple, sensitive and precise determination of total and specific types of glycosaminoglycans by laser nephelometry. The addition of the ammonium salt to solutions of various glycosaminoglycans in 0.03 mol/l NaCl produces a time-dependent increase in light scattering, which reaches a maximum between 14 and 18 h of complex formation, irrespective of the type of glycosaminoglycan studied. Only keratan sulphate does not generate light scattering, and is therefore not detectable by the procedure. The scattering of laser light by certain types of sulphated glycosaminoglycans (e.g. heparan sulphate, heparin) depends more on the degree of sulphation (charge density) than on chain length within a certain range. Optimum light scattering was found at 28 mmol/l N-cetylpyridinium chloride and at a ionic strength around 0.03 mol/l NaCl. The detection limits and linear ranges of the individual glycosaminoglycans were evaluated. For the determination of chondroitin sulphate, laser nephelometry is at least 8 times more sensitive and much more simple than the modified carbazole method (glucuronic acid). The intra-assay and inter-assay coefficients of variation are about 4% and 7%, respectively. Laser nephelometry is much more sensitive than turbidimetry. Complex synthetic mixtures of glycosaminoglycans and biological fluids were accurately differentiated by successive chemical and enzymatic degradation of the respective glycosaminoglycans followed by the measurement of the resulting reduction of laser light scattering. In synovial fluids from non-inflammatory joint diseases, light scattering (units/ml) was about 4.5 times higher than in synovial fluids from inflammatory articular lesions. In both pathologic conditions nearly all of the light scattering can be attributed to hyaluronic acid.

High-speed gel-permeation chromatography of glycosaminoglycans: its application to the analysis of heparan sulfate of embryonic carcinoma and its degradation products by tumor cell-derived heparanase

A high-speed gel-permeation chromatographic system for analyzing glycosaminoglycans which uses two 0.7 X 75-cm stainless-steel columns containing Fractogel (Toyopearl) TSK HW-55(S), was developed. Glycosaminoglycans were applied and eluted with a 0.2 M sodium chloride solution and monitored by ultraviolet absorption at 210 nm or radioactivity. The best resolution of glycans was obtained at 55 degrees C at a flow rate of 1.0 ml/min. Acidic and neutral glycans in the molecular weight (Mr) range 600-60,000 eluted within 45 min. A linear relationship was found between retention time and molecular weight using standard glycosaminoglycans, chitin oligosaccharides, and a porcine thyroglobulin glycoprotide. This system was used to analyze the heparan sulfate synthesized by PYS-2 embryonic carcinoma cells and the degradation products produced by incubating it with extracted glycosidases from metastatic B16 melanoma cells. The results indicated that B16 melanoma cells contain at least two different heparan sulfate degradative activities, one of which appears to be an endoglycosidase.

Absence of heparin or heparin-like compounds in mast-cell-free tissues and animals

Three models were used for the analysis of heparin concentration and the presence of mast cells, namely different fetal and adult bovine tissues, mast-cell-deficient mice and athymic mice. It was observed that heparin and mast cells are present mainly in spleen and liver during fetal development and in skin, lung and ileum in adults. A good correlation between the concentration of heparin and the number of mast cells was observed in all tissues examined. No heparin was detected in animals that did not have mast cells, such as the WBB6Fl W/Wv mice, again suggesting a correlation between mast cells and heparin. No differences in the other sulfated glycosaminoglycans were observed between the mast cell-deficient mice and the normal littermates and breeders. Studies in 'nude' mice have shown that the heparin concentration in different tissues is similar to normal strains.

Distribution of heparin and other sulfated glycosaminoglycans in vertebrates

1. A comparative study on the distribution of sulfated glycosaminoglycans in several tissues of six specimens of different vertebrate classes is reported. 2. Each tissue has a characteristic composition differing from each other regarding the relative amount, type and molecular size of chondroitin 4.6-sulfate, dermatan sulfate and heparan sulfate. 3. The same tissue from different vertebrates has, in general, the same types of sulfated glycosaminoglycans, but with different molecular weights. 4. Exception to this rule was observed for the distribution of heparin which was present only in a few tissues of the 6 vertebrates studied. 5. The possible involvement of the sulfated glycosaminoglycans in cell recognition and/or adhesiveness is discussed in view of this characteristic distribution.

Cell-surface heparan sulfate: an intercalated membrane proteoglycan

Two pools of heparan sulfate proteoglycans have been selectively solubilized from rat liver plasma membranes by successive incubations with heparin and detergent. The two populations of proteoglycans have similar polyanionic properties as indicated by identical elution positions on ion-exchange chromatography on DEAE-Sephacel but differ in buoyant density in CsCl when analyzed by density gradient centrifugation in the presence of 4 M guanidine. The detergent-extracted proteoglycan has a lower buoyant density (less than or equal to 1.40 g/ml) and is, as determined by gel chromatography, slightly larger than the heparin-released proteoglycan (buoyant density, greater than or equal to 1.55 g/ml). Furthermore, in contrast to the heparin-released proteoglycan, the detergent-extracted proteoglycan is able to bind detergent micelles, shows affinity for the hydrophobic gel octyl-Sepharose, and can be inserted into liposomes. We conclude that the detergent-extracted heparan sulfate represents a proteoglycan species that has its core protein rooted in the lipid bilayer of the plasma membrane.

Regulation of heparan sulphate metabolism by adenosine 3':5'-cyclic monophosphate in hepatocytes in culture

Freshly isolated rat hepatocytes maintained as monolayers in a serum-free medium synthesize sulphated glycosaminoglycans, most of which behave as heparan sulphate and are mainly distributed into intracellular compartments. Cyclic AMP, dibutyryl cyclic AMP, glucagon, noradrenaline, prostaglandin E(1), and theophylline, all drugs and hormones known to increase intracellular cyclic AMP concentrations, decreased the incorporation of (35)SO(4) (2-) into heparan sulphate of intra-, extra- and peri-cellular pools. The inhibition mediated by dibutyryl cyclic AMP was dose-dependent and observed as early as 2h after exposure to the drug. In the presence of 1mm-dibutyryl cyclic AMP, incorporation of (35)SO(4) (2-) or [(14)C]glucosamine into heparan sulphate was decreased to 40-50%, suggesting that dibutyryl cyclic AMP interfered with the synthesis of heparan sulphate. This was further supported by pulse-chase experiments, where dibutyryl cyclic AMP had no effect on the degradation of sulphated glycosaminoglycans. Heparan sulphates synthesized and secreted into the extracellular pool in the presence of dibutyryl cyclic AMP were smaller in size, whereas the degree of sulphation and molecular size of the heparan sulphate chains released by beta-elimination from these proteoglycans were not different from control values. In the presence of 1mm-cycloheximide, (35)SO(4) (2-) incorporation was decreased to 5%. Addition of p-nitrophenyl beta-d-xyloside, an artificial acceptor of glycosaminoglycan chain synthesis, enhanced this incorporation to 18%. Dibutyryl cyclic AMP did not have any inhibitory effect on the synthesis of chains initiated on p-nitrophenyl beta-d-xylosides. Incorporation of [(3)H]serine into heparan sulphate was not affected by dibutyryl cyclic AMP, whereas the degree of substitution of serine residues with heparan sulphate chains was less in heparan sulphate synthesized in the presence of dibutyryl cyclic AMP, suggesting that cyclic AMP exerts its effect on the metabolism of sulphated glycosaminoglycans by affecting the transfer of xylose on to the protein core.