Showing papers on "Chondroitin sulfate published in 1981"

Cultured endothelial cells produce heparinlike inhibitor of smooth muscle cell growth

Abstract: Using cultured cells from bovine and rat aortas, we have examined the possibility that endothelial cells might regulate the growth of vascular smooth muscle cells. Conditioned medium from confluent bovine aortic endothelial cells inhibited the proliferation of growth-arrested smooth muscle cells. Conditioned medium from exponential endothelial cells, and from exponential or confluent smooth muscle cells and fibroblasts, did not inhibit smooth muscle cell growth. Conditioned medium from confluent endothelial cells did not inhibit the growth of endothelial cells or fibroblasts. In addition to the apparent specificity of both the producer and target cell, the inhibitory activity was heat stable and not affected by proteases. It was sensitive flavobacterium heparinase but not to hyaluronidase or chondroitin sulfate ABC lyase. It thus appears to be a heparinlike substance. Two other lines of evidence support this conclusion. First, a crude isolate of glycosaminoglycans (TCA-soluble, ethanol-precipitable material) from endothelial cell-conditioned medium reconstituted in 20 percent serum inhibited smooth muscle cell growth; glycosaminoglycans isolated from unconditioned medium (i.e., 0.4 percent serum) had no effect on smooth muscle cell growth. No inhibition was seen if the glycosaminoglycan preparation was treated with heparinase. Second, exogenous heparin, heparin sulfate, chondroitin sulfate B (dermatan sulfate), chondroitin sulfate ABC, and hyaluronic acid were added to 20 percent serum and tested for their ability to inhibit smooth muscle cell growth. Heparin inhibited growth at concentrations as low as 10 ng/ml. Other glycosaminoglycans had no effect at doses up to 10 μg/ml. Anticoagulant and non- anticoagulant heparin were equally effective at inhibiting smooth muscle cell growth, as they were in vivo following endothelial injury (Clowes and Karnovsk. Nature (Lond.). 265:625-626, 1977; Guyton et al. Circ. Res. 46:625-634, 1980), and in vitro following exposure of smooth muscle cells to platelet extract (Hoover et al. Circ. Res. 47:578-583, 1980). We suggest that vascular endothelial cells may secrete a heparinlike substance in vivo which may regulate the growth of underlying smooth muscle cells.

Partial characterization of newly synthesized proteoglycans isolated from the glomerular basement membrane.

Abstract: Kidneys were perfused with [35S]sulfate at 4 h in vitro to radiolabel sulfated proteoglycans. Glomeruli were isolated from the labeled kidneys, and purified fractions of glomerular basement membrane (GBM) were prepared therefrom. Proteoglycans were extracted from GBM fractions by use of 4 M guanidine-HCl at 4 degrees C in the presence of protease inhibitors. The efficiency of extraction was approximately 55% based on 35S radioactivity. The extracted proteoglycans were characterized by gel-filtration chromatography (before and after degradative treatments) and by their behavior in dissociative CsCl gradients. A single peak of proteoglycans with an Mr of 130,000 (based on cartilage proteoglycan standards) was obtained on Sepharose CL-4B or CL-6B. Approximately 85% of the total proteoglycans were susceptible to nitrous acid oxidation (which degrades heparan sulfates), and approximately 15% were susceptible to digestion with chondroitinase ABC (degrades chondroitin-4 and -6 sulfates and dermatan sulfate). The released glycosaminoglycan (GAG) chains had an Mr of approximately 26,000. Density gradient centrifugation resulted in the partial separation of the extracted proteoglycans into two types with different densities: a heparan sulfate proteoglycan that was enriched in the heavier fraction (p greater than 1.43 g/ml), and a chondroitin sulfate proteoglycan that was concentrated in the lighter fractions (p less than 1.41). The results indicate that two types of proteoglycans are synthesized and incorporated into the GBM that are similar in size and consist of four to five GAG chains (based on cartilage proteoglycan standards). The chromatographic behavior of the extracted proteoglycans and the derived GAG, together with the fact that the two types of proteoglycans can be partially separated into the density gradient, suggest that the heparan sulfate and chondroitin sulfate(s) are located on different core proteins.

Involvement of cell surface heparin sulfate in the binding of lipoprotein lipase to cultured bovine endothelial cells.

Abstract: It has been postulated that lipoprotein lipase, an enzyme important in the uptake of fatty acids into tissues, is bound to the vascular endothelial cell surface and that this binding occurs through attachment to heparinlike glycosaminoglycans. Furthermore, it is thought that heparin releases the enzyme from its attachment to the endothelium into the circulation. These hypotheses have never been tested directly in cell systems in vitro. In the present study we have directly evaluated the interaction of lipoprotein lipase, purified from bovine skim milk with monolayer cultures of endothelial cells, isolated from bovine pulmonary artery. Endothelial cells in primary culture had no intrinsic lipoprotein lipase activity but were able to bind lipoprotein lipase quantitatively. The binding reached equilibrium and was saturable at 0.24 nmol of lipoprotein lipase/mg of cell protein. The concentration of lipoprotein lipase at half-maximal binding was 0.52 microM. Bound lipoprotein lipase could be detached from cultured cells by increasing concentrations of heparin, and at and above 0.6 microgram/ml of heparin, 90% of the cell-bound lipoprotein lipase activity was released. Heparan sulfate and dermatan sulfate released the enzyme to a lesser extent and chondroitin sulfate caused little, if any, release of lipoprotein lipase. The release of lipoprotein lipase with heparin was not associated with a release of [3S]glycosaminoglycans from 35S-prelabeled cells. Reductions of lipoprotein lipase binding to endothelial cells and of cell surface-associated [3S]glycosaminoglycans in 35S-prelabeled cells occurred in parallel both when cells were pretreated with crude Flavobacterium heparinum enzyme before lipoprotein lipase binding and when cells were treated with this enzyme after lipoprotein lipase binding. The removal of heparan sulfate from the cell surface by purified heparinase totally inhibited the binding of lipoprotein lipase by endothelial cells, but the removal of chondroitin sulfate by chondroitin ABC lyase had no effect on this binding. These results provide direct evidence for lipoprotein lipase attachment to endothelial cells through heparan sulfate on the cell surface, and provide evidence for the release of lipoprotein lipase by heparin through a detachment from this binding site.

Structural changes during development in bovine fetal epiphyseal cartilage.

Abstract: Sedimentation coefficients of approximately 150 S show that proteoglycan aggregates from bovine fetal epiphyseal cartilage are exceptionally large. To determine the structural basis for the unusually large size of these proteoglycan aggregates, identify changes in proteoglycan structure with changing developmental age, and provide a basis for demonstrating the structural modifications which may occur in growth plate proteoglycan aggregates during endochondral ossification, we examined the molecular architecture and dimensions of fetal epiphyseal proteoglycans by electron microscopy. The eight bovine epiphyseal cartilages studied ranged in fetal age from 168 to 241 days. Proteoglycans were extracted in 4 M guanidinium hydrochloride containing protease inhibitors and isolated by equilibrium density gradient centrifugation under associative and dissociative conditions. Electron micrographs were made from monolayer preparations of proteoglycan-cytochrome c mixtures on nitrocellulose support films. The overall molecular architecture of the proteoglycan aggregates from fetal epiphyseal cartilages was similar to that of aggregates from other cartilages and showed a single, unbranched central hyaluronic acid filament to which many proteoglycan monomers were attached. However, the dimensions of the fetal proteoglycans differed strikingly from those of proteoglycans from mature cow nasal or immature calf nasal cartilage. Specifically, proteoglycan aggregates from bovine fetal epiphyseal cartilage showed: (a) longer hyaluronic acid central filaments; (b) greater numbers of proteoglycan monomers per aggregate; (c) closer spacing of proteoglycan monomers along the hyaluronic acid central filament; and (d) longer proteoglycan monomer core proteins. Proteoglycan monomers bound to hyaluronate consisted of two segments: (1) a peripheral thick segment, composed of the chondroitin sulfate chains condensed along the peripheral portion of the protein core, which corresponds to the chondroitin sulfate-rich region; and, (2) a central thin segment, devoid of visible glycosaminoglycan chains, which attaches directly to the hyaluronic acid central filament and contains the hyaluronic acid binding region and a portion of the keratan sulfate-rich region. The contribution of the thin segment to total monomer length decreased as total monomer length increased. Thus, in longer monomers the thick segment contributed more to total monomer length and the thin segment contributed less. Both the thin and thick segments of monomers from fetal epiphyseal cartilage were longer than the corresponding segments of calf nasal cartilage and mature bovine nasal cartilage monomers.(ABSTRACT TRUNCATED AT 400 WORDS)

Glycosaminoglycans in human lung cancer

Abstract: The quantitative changes of glycosaminoglycans in tumor tissue of human lung cancers (2 squamous cell carcinomas, 4 adenocarcinomas and 5 small cell carcinomas) were studied. The total amount of glycosaminoglycans in human lung cancer tissues increased 1.4 to 4 times in comparison with that in normal lung tissues. The increase in tissue content of glycosaminoglycans was accompanied by an increase in the chondroitin sulfate level in every histologic type of lung cancer, as well as by a marked increase in hyaluronic acid level in squamous cell carcinomas, and a moderate increase in its level in small cell carcinomas. The concentrations of dermatan sulfate and heparan sulfate in lung cancer tissues did not show any significant changes compared with those in normal lung tissues. The increase in total amount and changes in the composition of glycosaminoglycans in human lung cancer tissue were closely related to the histologic type of the tumor.

Ultrastructure of the mouse synovial membrane

Abstract: The synovial membrane of the mouse knee joint was examined by electron microscopy and electron microscopic histochemistry, with special reference to the development of the extracellular matrix. In the embryonic synovium, the intercellular spaces were filled with hyaluronate and chondroitin sulfate. The formation of the early joint cavity appeared to be initiated by accumulation of hyaluronate and chondroitin sulfate in the synovial primordium. At the postnatal stage, the synovial primordium differentiated into a true synovial intima that could be easily identified by the presence of two distinct lining cells: fibroblast-like cells (B cells) and phagocytic cells (A cells). Simultaneously, the synovial intima provided the specialized extracellular matrix that was characterized by organized structures of micro-fibrils, collagen fibers, and fibrous long spacing fibers embedded in a large number of glycoproteins.

Urinary Glycosaminoglycan Excretion as a Biochemical Marker in Patients with Bladder Carcinoma

Abstract: Urinary glycosaminoglycan excretion was examined in 25 individuals with bladder cancer in comparison to glycosaminoglycan excretion by eight normal individuals. Urinary glycosaminoglycan was isolated by gel filtation and quantified as macromolecular uronate concentration. Electrophoresis in calcium acetate and densitometry of Alcian blue-stained electrophoretograms were used to separate and quantify the relative amounts of individual glycosaminoglycans. Elevated excretion of macromolecular uronate was noted in 53% of the cancer cases. The highest levels were found among individuals with metastatic disease. Three electrophoretic bands were always detected in the control and cancer groups: chondroitin sulfate, heparan sulfate (both confirmed by chemical and enzymatic degradation), and a third band (Band 1) of unknown composition. A fourth band, corresponding to dermatan sulfate, was seen in some high-grade metastatic tumors. Band 1 excretion was elevated in a significant fraction of all patients. Seven of 12 metastatic cases but only two of 13 localized cases showed increased heparan sulfate excretion. Diagnostic limits were drawn from the observed distributions of normals, and with these limits 92% of the cancer cases, including 12 of 12 metastatic cases, could be identified. The results strongly suggest noninvasive urinary glycosaminoglycan analysis may well provide a new biochemical approach for detecting and monitoring the pathogenesis of bladder cancer.

Glycosaminoglycans of pleural mesothelioma: a possible biochemical variant containing chondroitin sulfate.

Abstract: Glycosaminoglycans of a malignant pleural mesothelioma have been characterized histochemically and biochemically and compared with those of normal lung, pleural plaque, lung carcinoma, and other connective tissue neoplasms. Chondroitin sulfate constituted the major glycosaminoglycan (approximately 80% of total) present in the pleural mesothelioma while hyaluronic acid was present in only trace amounts (approximately 3% of total). In particular chondroitin 6-sulfate was the predominant isomer, constituting 80% of the total chondroitin sulfate. Control tissue exhibited different proportions of glycosaminoglycans and none of them contained as high an absolute concentration of chondroitin sulfate as the mesothelioma. These findings differ from previous reports demonstrating increased concentration of hyaluronic acid in mesothelioma and suggest the possible existence of a biochemically different form of this neoplasm.

Changes in Charge Density of Heparan Sulfate Isolated from Cancerous Human Liver Tissue

Abstract: Heparan sulfate fractions were isolated from three normal human livers and three cancerous human liver tissues, and their polyanionic properties were examined using electrophoresis, sequential partition fractionation, and chemical analyses. More than 60% of total glycosaminoglycans from normal human liver and about 30% from cancerous liver tissue were found to be heparan sulfate from their resistance to exhaustive digestion with chondroitinase ABC and their susceptibility to nitrous acid treatment. The heparan sulfate isolated from cancerous liver tissue afforded a lower sulfate/uronic acid molar ratio (0.58 to 0.65) than did normal human liver heparan sulfate (0.76 to 0.80). Also, the former showed lower electrophoretic mobility in 0.1 M HCl and a different partition fractionation profile in comparison with the latter. These differences in charge density of the macromolecule were not detected on the chondroitin sulfate and/or dermatan sulfate fractions isolated from normal human liver and cancerous liver tissue.

Correlation of specific sulfated glycosaminoglycans with collagen types I, II, and III

Abstract: A qualitative and quantitative biochemical study of the glycosaminoglycans was performed in tissues constituted predominantly by one type of collagen, or in tissues containing mixtures of different types of collagen. The results obtained show the presence of dermatan sulfate, chondroitin sulfate, and heparitin sulfate in tissues containing collagen types I, II, or III, respectively, suggesting a specific correlation of different glycosaminoglycans with these three types of collagen.

Aortic glycosaminoglycans in genetically selected WC-2 pigeons with increased atherosclerosis susceptibility.

Abstract: A genetically selected line of White Carneau pigeons (WC-2) was studied in an attempt to relate changes in composition and content of aortic glycosaminoglycan (GAG) to increased atherosclerosis susceptibility. The WC-2 pigeons were fed an atherogenic diet for 3 months and, when compared to randomly bred White Carneau (RBWC) controls, they showed similar plasma cholesterol concentrations but significantly greater aortic atherosclerosis. In the WC-2 pigeons, 35% of the aortic surface was covered with plaque compared with only 12% in RBWC pigeons; WC-2 birds showed cholesterol contents of 3.3 mg/aorta/500 g body weight, while the RBWC birds had only 0.9 mg/aorta/500 g body weight. After papain treatment of delipidated dried artery, the aortic GAG were isolated, purified using cetylpyridinium chloride, and identified and quantitated by a combination of procedure including selective enzymatic digestion and electrophoresis. In both pigeon groups, aortic GAG included 8% hyaluronic acid, 11% dermatan sulfate, 15% heparan sulfate, and 66% chondroitin sulfate. For the entire group, total aortic GAG content was 35% greater in WC-2 pigeons. Since we did not know if this increase in GAG was simply due to increased atherosclerosis in the WC-2 birds, we sorted the pigeons into matched groups representing minimal, moderate, and severe atherosclerosis on the basis of aortic cholesterol content. At all levels of cholesterol, all GAG contents were greater in the aortas of WC-2 pigeons. The accumulation of dermatan sulfate was 30% higher than in RBWC birds in the minimal arteriosclerosis group, 101% higher in the moderate group, and 53% higher in the severe group. Hyaluronic acid tended to decrease as aortic cholesterol contents increased in WC-2 pigeons. Reduced hyaluronic acid and increase dermatan sulfate may suggest the presence of an altered hyaluronic acid-dermatan sulfate-containing proteoglycan aggregate in the intercellular matrix of the WC-2 pigeon aorta. Possible consequences include increased artery permeability and a binding and retention of lipoproteins in the artery wall. These factors may explain why atherosclerosis develops at an increased rate in the WC-2 pigeon.

The effect of thyroid hormone on glycosaminoglycan accumulation in human skin fibroblasts

Abstract: Because the dermis of myxedematous humans is known to accumulate increased amounts of glycosaminoglycan (GAG), we were prompted to study the effects of thyroid hormone depletion in vitro. Human skin fibroblasts were grown to confluence in medium containing 10% fetal calf serum (FCS). Some cultures were shifted to a medium containing FCS depleted of thyroid hormone (D-FCS) or to a D-FCS medium to which 10(-7) M triiodothyronine (T3) was added (D-FCS + T3). Cultures were then labeled for 16 h with [3H]-acetate, harvested and combined with the media. After pronase digestion, the non-trichloroacetic acid precipitable, non-dialysable material was digested with streptomyces hyaluronidase followed by chondroitinase ABC. Digestable material was separated by G-50 Sephadex column chromatography. The cultures incubated in media containing D-FCS accumulated 2.8-fold more hyaluronic acid and 2.1-fold more chondroitin sulfate than did sister cultures incubated in the presence of D-FCS + T3. The addition of T3 to the D-FCS reduced the amounts of GAG accumulated nearly to the levels observed in cultures grown in FCS. The data indicate that thyroid hormone exerts an inhibitory effect on GAG accumulation in human skin fibroblasts. This model offers the opportunity to study thyroid hormone action in vitro using an easily accessible human tissue.

Comparison of proteoglycans extracted by saline and guanidinium chloride from cultured chick retinas.

Abstract: To compare the loosely associated sulfated proteoglycans with those tightly bound to membranes, retinas from 14-day chick embryos were subjected to progressively disruptive techniques. The most easily removed proteoglycans were isolated from the medium in which the tissue was labeled with [35S]sulfate. On the average, 25% of the glycosaminoglycans were in the labeling medium, 39% were in proteoglycans extracted from the tissue in the balanced salt solution, 32% were in a 4 M-guanidinium chloride (GuCl) fraction, and 4% remained unextracted. These glycosaminoglycans contained, respectively, 28, 28, 40, and 4% of the incorporated [35S]sulfate. On the basis of electrophoretic mobility and TLC of chondroitinase digests, the ratio of 35S in chondroitin sulfate to that in heparan sulfate was 4-7 times higher in the medium and balanced salt extracts than in the GuCl extracts. In both extracts there was more 35S in chondroitin-6-sulfate than in chondroitin-4-sulfate. Dialysis of the extracts against 0.5 M-NaCl resulted in the precipitation of about 12% of the glycosaminoglycans in the saline extracts and about 40% in GuCl extract. These subfractions, which were relatively enriched in heparan sulfate, were largely soluble in dithiothreitol in 8 M-urea (DTT). Similarities between the proteoglycans in the medium and those extracted by balanced salt solutions suggest that the saline-extracted proteoglycans were for the most part loosely associated with cell surfaces of extracellular matrices, whereas the GuCl-extracted proteoglycans probably were bound to membranes.