Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.2.2.7 (heparinase)
 1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the chemical nature of the cationic ferritin (CF)-binding sites of the differentiated microdomains of the capillary endothelium, the vasculature of the mouse pancreas and intestinal mucosa was perfused in situ with neuraminidase, hyaluronidase, chondroitinase ABC, heparinase, and three proteases: trypsin, papain, and pronase. Proteases of broad specificity removed all anionic sites, suggesting that the latter are contributed by acid glycoproteins or proteoglycans. Neuraminidase, hyaluronidase, and chondroitinase ABC reduced the density of CF-binding sites on the plasmalemma proper, but had no effect on either coated pits or fenestral diaphragms. Heparinase removed CF-binding sites from fenestral diaphragms and had no effect on coated pits. Taken together, these results indicate that the anionic sites of the fenestral diaphragms are contributed primarily by heparan sulfate and/or heparin, whereas those of the plasmalemma proper are of mixed chemical nature. The membranes and diaphragms of plasmalemmal vesicles and transendothelial channels do not bind CF in control specimens; this condition is not affected by the enzymic treatments mentioned above.
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PMID:Differentiated microdomains on the luminal surface of the capillary endothelium. II. Partial characterization of their anionic sites. 645 53

The distribution of anionic sites in the basal laminae of the blood capillaries of the murine pancreas was studied in specimens fixed in ruthenium red (RR)-glutaraldehyde mixtures. The sites appeared as discrete, small (6 to 18 nm) particles distributed throughout the three laminae but concentrated primarily in the lamina rara externa, in which--spaced 80-100 nm apart--they formed a planar, partially ordered lattice comparable to that revealed by cationized ferritin in previous studies (M. Simionescu, N. Simionescu, and G. E. Palade, 1982, J. Cell Biol. 95, 425-434). The chemical nature of the anionic sites was explored by incubating fresh tissue specimens in solutions of selected enzymes before fixation in RR-glutaraldehyde mixtures. Pronase P and papain removed completely the anionic sites and left behind an extensively degraded and disorganized basal lamina. Trypsin caused the removal of anionic sites only, did not degrade the rest of the basal lamina, but detached it completely from the endothelium. Chondroitinase ABC reduced slightly the size and the surface density of RR-stainable particles, and detached focally the rest of the basal lamina from the endothelium and pericytes. Crude heparinase caused a nearly complete removal of anionic sites, and pure heparitinase gave comparable but less extensive results. Similar effects were recorded on the basal laminae of smooth muscle fibers and pancreatic acini and ducts. The results indicate that the anionic sites of all basal laminae examined are contributed primarily by heparin sulfate proteoglycans and trace amounts of chondroitin sulfate proteoglycans.
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PMID:Partial chemical characterization of the anionic sites in the basal lamina of fenestrated capillaries. 652 60

The relative distribution of heparan sulfate-glycosaminoglycan (HS-GAG) and chondroitin sulfate-glycosaminoglycans (CS-GAG) of the mesangial matrix (MM) and the glomerular basement membrane (GBM), which represent the two glomerular extracellular matrices, was determined by a combination of enzymatic treatments and autoradiographic methods. The kidneys were digested in situ either with heparinase (degrades HS and CS-GAG) or chondroitinase-ABC (degrades CS-GAG). Subsequently, the sulfated GAGs were labeled with a radioiodinated analog of cationic ferritin (CF, pI approximately 7.5). The tissues were then processed for light and electron microscopic autoradiography. The autoradiographic analysis showed that sulfated GAGs are distributed both in the GBM and mesangial matrix. The predominant GAG present in both the matrices is HS-GAG and the CS-GAG is exclusively present in the mesangial matrix. These data indicate that the GBM and mesangial matrix are compositionally different. These differences may be of importance in the establishment of normal glomerular function and organization and in the alteration of that function and organization as a result of various disease processes, especially of those that are immune-complex mediated.
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PMID:Distribution of sulfated glycosaminoglycans in the glomerular basement membrane and mesangial matrix. 664 40

Alterations in the permeability of the glomerular basement membrane (GBM) towards native ferritin (NF) and iodinated albumin (125I-BSA) following removal of the major glycosaminoglycans (GAGs) of the GBM, heparan sulfate (HS) and hyaluronic acid (HA), were assessed utilizing the techniques of routine electron microscopy and autoradiography, respectively. Kidneys were incubated with heparinase (to degrade the GAGs of the GBM) and subsequently perfused with either NF or 125I-BSA. Control kidneys, which were not treated with heparinase, showed a low permeability to both tracers, with NF being confined to the lamina rara interna and 125I-BSA exhibiting a low level of passage into the urinary spaces (as indicated by a low density of autoradiographic grains over the urinary spaces). After heparinase treatment there was an increase in the permeability of the GBM such that both NF and 125I-BSA passed through the GBM in larger quantities and entered the urinary spaces. Perfusion of cationized ferritin (CF) into control kidneys revealed this probe to bind to the HS-rich anionic sites present within the GBM. Treatment with heparinase resulted in an abolition of the CF binding thereby indicating that the sites are composed mainly of HS and that HS plays a key role in establishing the permeability properties of the GBM. The changes in the pattern of distribution and density of the anionic sites of the GBM following induction of nephrosis was also studied. Animals were rendered nephrotic by subcutaneous injections of an aminonucleoside of puromycin and their kidneys subsequently perfused with either CF or cationized cytochrome c. No difference in either the pattern of distribution on density of the anionic sites in the GBM of nephrotic kidneys was observed when compared to nonnephrotic controls; thus indicating that the proteinuria associated with aminonucleoside nephrosis might be due to changes in components of the glomerular capillary wall other than the anionic sites.
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PMID:Glycosaminoglycans of the glomerular basement membrane in normal and nephrotic states. 730 62


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