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Query: EC:3.2.1.36 (hyaluronidase)
 4,606 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distribution of sclerotome and neural crest cells of avian embryos was studied by light and electron microscopy. Sclerotome cells radiated from the somites towards the notochord, to occupy the perichordal space. Neural crest cells, at least initially, also entered cell-free spaces. At the cranial somitic levels they moved chiefly dorsal to the somites, favouring the rostral part of each somite. These cells did not approach the perichordal space. More caudally (i.e. trunk levels), neural crest cells initially moved ventrally between the somites and neural tube. Adjacent to the caudal half of each somite, these cells penetrated no further than the myosclerotomal border, but opposite the rostral somite half, they were found next to the sclerotome almost as far ventrally as the notochord. However, they did not appear to enter the perichordal space, in contrast to sclerotome cells. When tested in vitro, sclerotome cells migrated towards notochords co-cultured on fibronectin-rich extracellular material, and on collagen gels. In contrast, neural crest cells avoided co-cultured notochords. This avoidance was abolished by inclusion of testicular hyaluronidase and chondroitinase ABC in the culture medium, but not by hyaluronidase from Streptomyces hyalurolyticus. The results suggest that sclerotome and neural crest mesenchyme cells have a different distribution with respect to the notochord, and that differential responses to notochordal extracellular material, possibly chondroitin sulphate proteoglycan, may be responsible for this.
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PMID:Morphogenesis of sclerotome and neural crest in avian embryos. In vivo and in vitro studies on the role of notochordal extracellular material. 371 66

The neural crest is a population of highly migratory mesenchymal cells that ultimately localize in specific sites and differentiate into a variety of cell types. This report describes studies on the factors governing the migratory pathways, differentiation, and ultimate localization of the neural crest-derived pigment cells (black melanophores and yellow xanthophores) in the California newt, Taricha torosa. Melanophores first appear scattered in the dorsal portion of the lateral neural crest migratory pathway (between the somites and the ectoderm). These cells are eventually found in two stripes: a dorsal stripe that runs along the apex of the somites, and a midbody stripe near the somite-lateral plate mesoderm border. Melanophores are not seen in the dorsal fin of prehatching embryos. Xanthophores can be identified with the light microscope using NH4OH-induced autofluorescence of pteridines and in the transmission electron microscope (TEM) by the presence of pterinosomes. Xanthophores first appear scattered among the melanophores over the surface of the somites; these cells eventually are found between the two melanophore stripes and in the dorsal fin. We were interested in determining the roles of the extracellular matrix (ECM) in controlling the formation of pigment cell patterns in T. torosa. Immunocytochemistry, Alcian blue staining of paraffin sections and ruthenium red staining of thin sections (accompanied by Streptomyces hyaluronidase and chondroitinase ABC digestion) were used to identify the composition and distribution of the ECM surrounding the pigment cells at various stages during development. The adhesive glycoprotein fibronectin is found in the dorsal portion of the lateral neural crest migratory pathway as well as in the dorsal fin matrix. Glycosaminoglycans (GAG) are found primarily in the dorsal fin and in the ECM surrounding the notochord. The dorsal fin ECM contains hyaluronate (HA), which was identified in the TEM as Streptomyces hyaluronidase-sensitive 3-5 nm microfibrils, as well as sulfated proteoglycan aggregates. We then confronted T. torosa neural crest cells in vitro with known ECM molecules. When neural folds are explanted onto tissue culture plastic in half-strength L-15 medium containing 10% fetal calf serum (FCS), cells migrate from the explant and differentiate into melanophores after 6 to 9 days. Xanthophores appear in the cultures 2 to 4 days after the appearance of melanophores. When cultured on three-dimensional collagen gels, xanthophores migrate significantly farther (P less than 0.01) onto and into the collagen than melanophores (336 +/- 183 vs 196 +/- 160 microns from the edge of the explant).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pigment cell pattern formation in Taricha torosa: the role of the extracellular matrix in controlling pigment cell migration and differentiation. 377 Mar 3

Among the most important events in connective tissue physiology are the nucleation, growth and calcification of collagen fibrils. It has been speculated that all are associated with, or even controlled by collagen-proteoglycan interactions. We therefore developed methods for investigating these associations in tissues, particularly for understanding their significance for type I collagen, the commonest form of collagen in the body, especially predominant in bone. Using an electron-dense dye, Cupromeronic blue, in the 'critical electrolyte concentration' mode, and digestion by hyaluronidase, chondroitinase ABC or keratanase, supported by biochemical analyses, we found that dermatan sulphate proteoglycan of soft connective tissue (skin, tendon, cornea) was regularly and orthogonally arrayed at the fibril surface, at the d or e band. Keratan sulphate proteoglycan in the cornea associates orthogonally at the a and c bands. Bone, demineralized by a non-aqueous technique which retains proteoglycans in the tissue, does not contain orthogonal arrays; the interfibrillar proteoglycan filaments are oriented parallel to the fibril axis. The main proteoglycan in bone is chondroitin sulphate-rich. There are thus four separate specific binding sites on type I collagen fibrils, each one associating with one particular proteoglycan, and apparently no other. This implies that there are two corresponding binding sites in each proteoglycan. Available evidence shows that there are two species of small dermatan sulphate and keratan sulphate proteoglycans. It is suggested that each species is specific for its own band (a, c, d or e). Hyaluronate and chondroitin sulphate are probably mainly interfibrillar, acting in a space-filling capacity.
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PMID:Proteoglycan-collagen interactions. 381 15

Studies of the structure and synthesis of cartilage proteoglycan core protein have been carried out. Deglycosylation of completed, secreted proteoglycan by HF-pyridine treatment yielded an intact homogeneous core protein of approximately 210,000 daltons, with a blocked amino-terminus. Greater than 95% of chondroitin sulfate chains and 80% of N- and O-linked oligosaccharides were removed by the procedure, which made the product an excellent xylosyltransferase acceptor. Little alteration of core protein structure occurred during the HF-pyridine treatment as shown by complete immunoreactivity with antiserums prepared against hyaluronidase-digested proteoglycan. In other studies, the initially synthesized precursor for proteoglycan core protein was found to be approximately 376,000 daltons and localized to the rough membrane fractions. This precursor already contained N-linked oligosaccharides, and was also able to accept xylose, thereby initiating chondroitin sulfate chains. The precursor was translocated intact in an energy-dependent manner to smooth membrane-Golgi fractions where further processing of high mannose type of oligosaccharides and addition of glycosaminoglycan chains occurred. The subcellular distribution pattern of the chondroitin sulfate-synthesizing enzymes corroborated the proposed topological modifications of the proteoglycan core protein precursor.
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PMID:Synthesis and structure of proteoglycan core protein. 391 43

Mesodermal cells in the developing chick embryo limb bud appear morphologically homogeneous until stage 21. At stage 22 the prechondrogenic and premyogenic areas begin to condense, culminating in the appearance of cartilage and muscle by stage 25-26. We have examined changes in the hyaluronate-dependent pericellular matrices elaborated by mesodermal cells of the limb bud from different developmental stages and the corresponding changes in production of cell surface-associated and secreted glycosaminoglycans. When placed in culture, most early mesodermal cells (stage 17 lateral plate and stage 19 limb bud) exhibited pericellular coats as visualized by the exclusion of particles. These coats were removed by treatment of the cultures with Streptomyces hyaluronidase. Cells from stage 20-21 limb buds (precondensation) had smaller coats, whereas cells derived from stage 22, 24, and 26 limb buds (condensed chondrogenic and myogenic regions) lacked coats. However, coats were reformed during subsequent cytodifferentiation of chondrocytes; chondrocytes from stage 28 and 30 limb buds, and more mature chondrocytes from stage 38 tibiae, had pericellular coats. Thus, cytodifferentiation of cartilage is accompanied by extensive intercellular matrix accumulation in vivo and reacquisition of pericellular coats in vitro. Although their structure was still dependent on hyaluronate, chondrocyte coats were associated with increased proteoglycan content compared to the coats of early mesodermal cells. The amount of incorporation of [3H]acetate into cell surface hyaluronate remained relatively constant from stages 17 to 38, whereas in the medium compartment, incorporation into hyaluronate was more than 4-fold greater by stage 17 and 19 mesodermal cells than by cells from stages between 20 and 38. However, there was a progressive increase in incorporation into cell surface and medium chondroitin sulfate throughout these developmental stages. Thus, at the time of cellular condensation in the limb bud in vivo, we have observed a reduction in size of hyaluronate-dependent pericellular coats and a dramatic change in the relative proportion of hyaluronate and chondroitin sulfate produced by the mesodermal cells in vitro.
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PMID:Changes in the pericellular matrix during differentiation of limb bud mesoderm. 393 2

The association of proteoglycans with type I collagen fibrils in skin, tendon, cornea and bone has been determined by electron microscopy using an electron-dense dye, Cupromeronic blue, in the critical electrolyte concentration mode, backed up by biochemical analysis and digestion by hyaluronidase or keratanase. A major proteoglycan of the soft tissues, containing dermatan sulphate, is shown to be regularly and orthogonally arranged at the surface of the fibrils. Uranyl acetate counterstaining revealed that the main specific binding site is the 'd' band, which previous work indicated is very close to the initial site of calcification of type I collagen fibrils. Bone, demineralized by a 'non-aqueous' technique which preserves the proteoglycan in the tissue, does not contain orthogonal arrays; the interfibrillar proteoglycan filaments are oriented parallel to the fibril axis. The main proteoglycan in bone is chondroitin sulphate-rich. It is suggested that dermatan sulphate proteoglycan plays a role in preventing soft connective tissues from calcifying.
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PMID:Proteoglycan-type I collagen fibril interactions in bone and non-calcifying connective tissues. 398 11

Binding of fibronectins (FN) to collagen types I-IV were studied using polyclonal antibodies against human and chicken FNs, proteoglycan monomers, collagen type II and monoclonal antibodies reacting with both soluble and insoluble forms of human FN. Plasma fibronectin and type II collagen were shown to interact specifically in a homologous system. Type II collagen, however, proved to be less effective in inhibition assays compared to other types of collagen. In high density cultures of chicken limb bud cells, fibronectin was first localized within the fibroblast-like cells of 4 hr cultures and an extensive extracellular filamentous network developed by the end of day 1. Fibronectin was present in the newly formed cartilage nodules although it seemed to disappear by day 6, when the proteoglycan accumulation became more intensive. Enzyme treatments (testicular hyaluronidase, chondroitinase ABC) helped to localize FN at this stage of development of chicken cartilage, in microdroplet high density cultures of human fetal chondrocytes and in articular cartilage. Fibronectin was localized only in the pericellular ring of intact human articular cartilage using monoclonal antibodies with the biotin-avidin system.
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PMID:Appearance and persistence of fibronectin in cartilage. Specific interaction of fibronectin with collagen type II. 399 52

Two collagen-poor, ultramicroscopic layers are described at the surface of canine articular cartilage. They are distinguished by staining with an electron-dense cationic dye, Cupromeronic Blue, in a critical electrolyte concentration technique and by digestion with testicular hyaluronidase. The superficial layer, approximately 50 nm thick, stained at low electrolyte concentrations but failed to stain in conditions specific for sulphated glycosaminoglycans. It was hyaluronidase-resistant and may be either glycoprotein or protein in nature. The deeper layer, 100-400 nm thick, stained positively at electrolyte concentrations specific for sulphated glycosaminoglycans but not in conditions specific for keratan sulphate. It was removed by hyaluronidase digestion. This layer probably represents a chondroitin sulphate-rich proteoglycan. These surface layers may be important in the lubrication of the articular surface and in the permeability and compression resistance of the superficial cartilage zone.
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PMID:Ultrastructural histochemistry of the surface lamina of normal articular cartilage. 401 50

Interaction between cartilage proteoglycan and the collagen(s) composed of 1 alpha, 2 alpha, and 3 alpha chains was studied in vitro. Most of the collagen was insoluble under the conditions of assay (0.15 M NaCl, 0.008 M phosphate buffer, pH 7.4; 4 degrees C) and was in the form of fibrils 20 nm in diameter or thinner. The larger fibrils had 60-70 nm periodicity, characteristic of native collagens. Proteoglycan monomers which had been labeled by incubating cartilage slices in vitro with Na2 35SO4 were used to assay the interaction. The insoluble collagen fraction bound proteoglycan from solution. At proteoglycan:collagen ratios lower than 1:2, binding was rapid and linear, and the dissociation constant was 1.7 X 10(-9) M. At higher proteoglycan:collagen ratios, more proteoglycan was bound, but at a slower rate. Binding of proteoglycan to collagen did not require fibrils, since soluble 1 alpha, 2 alpha, and 3 alpha containing collagen also bound to proteoglycan and formed an insoluble complex. Denatured collagens did not bind proteoglycan or compete for binding with normal collagen. Optimum binding occurred with intact proteoglycan, but proteoglycan which had been treated with protease was also bound at low levels. Both protease-treated proteoglycan and free chondroitin sulfate competed with intact proteoglycan in the binding assays, but neither chondroitinase ABC-treated proteoglycan nor the oligosaccharides produced by digestion of chondroitin sulfate with testicular hyaluronidase altered the binding of proteoglycan to collagen. Hyaluronic acid did not compete with radioactive proteoglycan, but heparin and dextran sulfate were extremely effective inhibitors of binding. These data suggest a relatively nonspecific interaction between sulfated polyanions and 1 alpha, 2 alpha, and 3 alpha containing collagens. However, given the location of these collagens near the chondrocyte surface, the interaction of fibrillar 1 alpha, 2 alpha, 3 alpha collagen with proteoglycan is likely to occur and to be of biological importance.
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PMID:Interaction of proteoglycans with the pericellular (1 alpha, 2 alpha, 3 alpha) collagens of cartilage. 403 Jul 69

The hyaluronic acid binding region was prepared by clostripain digestion of chondroitin sulfate proteoglycan isolated from the Swarm rat chondrosarcoma, and biotinylated in the presence of associated hyaluronic acid and link protein. After removal of hyaluronic acid by gel filtration in 4 M guanidine HCl, the biotinylated binding region-link protein complex was used as a specific histochemical probe in conjunction with avidin-peroxidase. Its utility was initially evaluated by comparison with Alcian blue staining of the axial region of 2 to 5 day chick embryos, where staining was seen in the dorsolateral area between the neural tube and the ectoderm, in the perichordal mesenchyme, and in developing limb buds. Light and electron microscopic studies of early postnatal rat cerebellum indicate that hyaluronic acid is primarily localized in the extracellular space of immature brain. Staining specificity was demonstrated by the ability of hyaluronic acid oligosaccharides of appropriate size to block the staining reaction, and by the absence of staining after treatment of tissue sections with protease-free Streptomyces hyaluronidase, which degrades only this glycosaminoglycan.
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PMID:The hyaluronic acid binding region as a specific probe for the localization of hyaluronic acid in tissue sections. Application to chick embryo and rat brain. 404 84


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