The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
John J. Robinson - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of Hyalin gelation an essential step in the assembly of the sea urchin extraembryonic matrix the Hyaline layer
Archives of Biochemistry and Biophysics, 2003Co-Authors: Robert Rimsay, John J. RobinsonAbstract:We have examined the effects of calcium and magnesium on both the structural characteristics and the self-association reaction of Hyalin, a major protein component of the sea urchin extraembryonic matrix, the Hyaline layer. In the absence of calcium, the circular dichroic spectrum revealed a protein possessing a high β sheet content. The presence of increasing concentrations of calcium resulted in an increase in β sheet content and a coincidental decrease in α helix. This effect occurred with an apparent dissociation constant (calcium) of 1.5 mM. The calcium-induced structural change was potentiated by magnesium. Similar concentrations of calcium protected Hyalin from digestion by trypsin and this effect was potentiated by magnesium. The thermal denaturation profile of Hyalin was modulated by calcium. At a concentration of 3 mM, calcium protected Hyalin from thermal denaturation, an effect partially mimicked, but not potentiated, by magnesium. Calcium was also found to modulate both the intensity and the wavelength of maximal, endogenous tryptophan fluorescence. The effect of calcium on Hyalin tertiary structure had a concentration dependence decidedly different from those reported above with an apparent dissociation constant of 0.18 mM. Collectively, these results delineate two distinct roles for calcium in modulating Hyalin structure and allow us to define the pathway leading to Hyalin-gel formation.
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Hyalin a sea urchin extraembryonic matrix protein relationship between calcium binding and Hyalin gelation
Archives of Biochemistry and Biophysics, 1992Co-Authors: John J. Robinson, Douglas E Hall, Christina Brennan, Penny KeanAbstract:Abstract The protein Hyalin, a major component of the sea urchin extraembryonic Hyaline layer, was previously shown to undergo a Ca 2+ -induced self-association into large aggregates (gelation). This reaction represented a major step in assembly of the layer. In the experiments reported here, digestion with trypsin resulted in a rapid dissociation of Hyalin into a mixture of peptides which retained the capacity to bind Ca 2+ . However, unlike intact Hyalin, none of these peptides associated into large aggregates (gelation) in the presence of Ca 2+ , Mg 2+ , and NaCl. Loss of the ability to undergo gelation was not accompanied by any significant change in the content of acidic plus amide amino acid residues. Decreasing the pH to 5.6 resulted in a loss of 25% of Hyalin's Ca 2+ -binding capacity but had no effect on the ability of the protein to undergo gelation. Peptide fragments were only partially effective at inhibiting Hyalin gelation. Clearly, not all the Ca 2+ -binding sites were required for Hyalin gelation and Ca 2+ binding alone was insufficient to drive this reaction. In addition, Hyalin appeared to possess two classes of protein-protein interaction domains, one of which was essential for gelation.
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assembly of the sea urchin extraembryonic Hyaline layer ca2 and mg2 act independently and at different sites on the pathway leading to Hyalin gel formation
Archives of Biochemistry and Biophysics, 1991Co-Authors: John J. Robinson, Christina BrennanAbstract:We have studied the interactions of Ca2+ with the sea urchin extraembryonic coat protein Hyalin. As reported previously, Ca2+ alone was ineffective in inducing Hyalin-gel (large aggregate) formation. This reaction required the additional presence of Mg2+ and NaCl. However, the results of tryptic digestion and nondenaturing agarose gel electrophoresis experiments demonstrated that Ca2+ could induce Hyalin self-association into small aggregates in the absence of Mg2+ and NaCl. Magnesium did not modulate the interactions of Ca2+ with Hyalin. In addition, Mg2+ had minimal effects on the conformation of Hyalin. These results have been incorporated into a model delineating the pathway leading to Hyalin-gel formation.
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ca2 binding and protein protein interaction domains of the sea urchin extraembryonic coat protein Hyalin
International Journal of Biochemistry, 1991Co-Authors: John J. RobinsonAbstract:1. 1. As reported previously (Hopper and Robinson, 1990; Int. J. Biochem. 22, 1165–1170) the sea urchin extraembryonic coat protein Hyalin undergoes a Ca2+-induced self-association into an insoluble gel (gelation) in the presence of Mg2+ and/or NaCl. 2. 2. A 275 kDa peptide fragment, generated by limited tryptic digestion of Hyalin, binds Ca2++ but does not undergo gelation in the presence of Ca2+, Mg2+ and NaCl. 3. 3. Comparisons between the capacities of Hyalin and the 275 kDa peptide fragment to bind Ca2+ indicate that the latter binds 88% less Ca2+ than Hyalin. 4. 4. However, the presence of Ca2+ alone, at a concentration of 5 mM, protects the 275 kDa peptide fragment from further digestion by trypsin mimicking the effect of this cation in protecting Hyalin. 5. 5. Gel exclusion Chromatographie analyses of the 275 kDa peptide fragment, both in the presence and absence of 5 mM Ca2+, indicate that this cation does induce self-association of the fragment. 6. 6. These results provide information on the organization of the functional domains on Hyalin which are required for gel formation.
Christina Brennan - One of the best experts on this subject based on the ideXlab platform.
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Hyalin a sea urchin extraembryonic matrix protein relationship between calcium binding and Hyalin gelation
Archives of Biochemistry and Biophysics, 1992Co-Authors: John J. Robinson, Douglas E Hall, Christina Brennan, Penny KeanAbstract:Abstract The protein Hyalin, a major component of the sea urchin extraembryonic Hyaline layer, was previously shown to undergo a Ca 2+ -induced self-association into large aggregates (gelation). This reaction represented a major step in assembly of the layer. In the experiments reported here, digestion with trypsin resulted in a rapid dissociation of Hyalin into a mixture of peptides which retained the capacity to bind Ca 2+ . However, unlike intact Hyalin, none of these peptides associated into large aggregates (gelation) in the presence of Ca 2+ , Mg 2+ , and NaCl. Loss of the ability to undergo gelation was not accompanied by any significant change in the content of acidic plus amide amino acid residues. Decreasing the pH to 5.6 resulted in a loss of 25% of Hyalin's Ca 2+ -binding capacity but had no effect on the ability of the protein to undergo gelation. Peptide fragments were only partially effective at inhibiting Hyalin gelation. Clearly, not all the Ca 2+ -binding sites were required for Hyalin gelation and Ca 2+ binding alone was insufficient to drive this reaction. In addition, Hyalin appeared to possess two classes of protein-protein interaction domains, one of which was essential for gelation.
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assembly of the sea urchin extraembryonic Hyaline layer ca2 and mg2 act independently and at different sites on the pathway leading to Hyalin gel formation
Archives of Biochemistry and Biophysics, 1991Co-Authors: John J. Robinson, Christina BrennanAbstract:We have studied the interactions of Ca2+ with the sea urchin extraembryonic coat protein Hyalin. As reported previously, Ca2+ alone was ineffective in inducing Hyalin-gel (large aggregate) formation. This reaction required the additional presence of Mg2+ and NaCl. However, the results of tryptic digestion and nondenaturing agarose gel electrophoresis experiments demonstrated that Ca2+ could induce Hyalin self-association into small aggregates in the absence of Mg2+ and NaCl. Magnesium did not modulate the interactions of Ca2+ with Hyalin. In addition, Mg2+ had minimal effects on the conformation of Hyalin. These results have been incorporated into a model delineating the pathway leading to Hyalin-gel formation.
Jiro Maegawa - One of the best experts on this subject based on the ideXlab platform.
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brief report reconstruction of joint Hyaline cartilage by autologous progenitor cells derived from ear elastic cartilage
Stem Cells, 2014Co-Authors: Mitsuru Mizuno, Takanori Takebe, Yuichiro Yabuki, Takahisa Matsuzaki, Lee Jeong Ik, Hiroshi Yoshikawa, Shinji Kobayashi, Seiichiro Nakabayashi, Jiro MaegawaAbstract:In healthy joints, Hyaline cartilage covering the joint surfaces of bones provides cushioning due to its unique mechanical properties. However, because of its limited regenerative capacity, age- and sports-related injuries to this tissue may lead to degenerative arthropathies, prompting researchers to investigate a variety of cell sources. We recently succeeded in isolating human cartilage progenitor cells from ear elastic cartilage. Human cartilage progenitor cells have high chondrogenic and proliferative potential to form elastic cartilage with long-term tissue maintenance. However, it is unknown whether ear-derived cartilage progenitor cells can be used to reconstruct Hyaline cartilage, which has different mechanical and histological properties from elastic cartilage. In our efforts to develop foundational technologies for joint Hyaline cartilage repair and reconstruction, we conducted this study to obtain an answer to this question. We created an experimental canine model of knee joint cartilage damage, transplanted ear-derived autologous cartilage progenitor cells. The reconstructed cartilage was rich in proteoglycans and showed unique histological characteristics similar to joint Hyaline cartilage. In addition, mechanical properties of the reconstructed tissues were higher than those of ear cartilage and equal to those of joint Hyaline cartilage. This study suggested that joint Hyaline cartilage was reconstructed from ear-derived cartilage progenitor cells. It also demonstrated that ear-derived cartilage progenitor cells, which can be harvested by a minimally invasive method, would be useful for reconstructing joint Hyaline cartilage in patients with degenerative arthropathies. Stem Cells 2014;32:816–821
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brief report reconstruction of joint Hyaline cartilage by autologous progenitor cells derived from ear elastic cartilage
Stem Cells, 2014Co-Authors: Mitsuru Mizuno, Takanori Takebe, Yuichiro Yabuki, Takahisa Matsuzaki, Hiroshi Yoshikawa, Shinji Kobayashi, Seiichiro Nakabayashi, Hiroomi Kan, Jiro MaegawaAbstract:In healthy joints, Hyaline cartilage covering the joint surfaces of bones provides cushioning due to its unique mechanical properties. However, because of its limited regenerative capacity, age- and sports-related injuries to this tissue may lead to degenerative arthropathies, prompting researchers to investigate a variety of cell sources. We recently succeeded in isolating human cartilage progenitor cells from ear elastic cartilage. Human cartilage progenitor cells have high chondrogenic and proliferative potential to form elastic cartilage with long-term tissue maintenance. However, it is unknown whether ear-derived cartilage progenitor cells can be used to reconstruct Hyaline cartilage, which has different mechanical and histological properties from elastic cartilage. In our efforts to develop foundational technologies for joint Hyaline cartilage repair and reconstruction, we conducted this study to obtain an answer to this question. We created an experimental canine model of knee joint cartilage damage, transplanted ear-derived autologous cartilage progenitor cells. The reconstructed cartilage was rich in proteoglycans and showed unique histological characteristics similar to joint Hyaline cartilage. In addition, mechanical properties of the reconstructed tissues were higher than those of ear cartilage and equal to those of joint Hyaline cartilage. This study suggested that joint Hyaline cartilage was reconstructed from ear-derived cartilage progenitor cells. It also demonstrated that ear-derived cartilage progenitor cells, which can be harvested by a minimally invasive method, would be useful for reconstructing joint Hyaline cartilage in patients with degenerative arthropathies.
Seiichiro Nakabayashi - One of the best experts on this subject based on the ideXlab platform.
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brief report reconstruction of joint Hyaline cartilage by autologous progenitor cells derived from ear elastic cartilage
Stem Cells, 2014Co-Authors: Mitsuru Mizuno, Takanori Takebe, Yuichiro Yabuki, Takahisa Matsuzaki, Lee Jeong Ik, Hiroshi Yoshikawa, Shinji Kobayashi, Seiichiro Nakabayashi, Jiro MaegawaAbstract:In healthy joints, Hyaline cartilage covering the joint surfaces of bones provides cushioning due to its unique mechanical properties. However, because of its limited regenerative capacity, age- and sports-related injuries to this tissue may lead to degenerative arthropathies, prompting researchers to investigate a variety of cell sources. We recently succeeded in isolating human cartilage progenitor cells from ear elastic cartilage. Human cartilage progenitor cells have high chondrogenic and proliferative potential to form elastic cartilage with long-term tissue maintenance. However, it is unknown whether ear-derived cartilage progenitor cells can be used to reconstruct Hyaline cartilage, which has different mechanical and histological properties from elastic cartilage. In our efforts to develop foundational technologies for joint Hyaline cartilage repair and reconstruction, we conducted this study to obtain an answer to this question. We created an experimental canine model of knee joint cartilage damage, transplanted ear-derived autologous cartilage progenitor cells. The reconstructed cartilage was rich in proteoglycans and showed unique histological characteristics similar to joint Hyaline cartilage. In addition, mechanical properties of the reconstructed tissues were higher than those of ear cartilage and equal to those of joint Hyaline cartilage. This study suggested that joint Hyaline cartilage was reconstructed from ear-derived cartilage progenitor cells. It also demonstrated that ear-derived cartilage progenitor cells, which can be harvested by a minimally invasive method, would be useful for reconstructing joint Hyaline cartilage in patients with degenerative arthropathies. Stem Cells 2014;32:816–821
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brief report reconstruction of joint Hyaline cartilage by autologous progenitor cells derived from ear elastic cartilage
Stem Cells, 2014Co-Authors: Mitsuru Mizuno, Takanori Takebe, Yuichiro Yabuki, Takahisa Matsuzaki, Hiroshi Yoshikawa, Shinji Kobayashi, Seiichiro Nakabayashi, Hiroomi Kan, Jiro MaegawaAbstract:In healthy joints, Hyaline cartilage covering the joint surfaces of bones provides cushioning due to its unique mechanical properties. However, because of its limited regenerative capacity, age- and sports-related injuries to this tissue may lead to degenerative arthropathies, prompting researchers to investigate a variety of cell sources. We recently succeeded in isolating human cartilage progenitor cells from ear elastic cartilage. Human cartilage progenitor cells have high chondrogenic and proliferative potential to form elastic cartilage with long-term tissue maintenance. However, it is unknown whether ear-derived cartilage progenitor cells can be used to reconstruct Hyaline cartilage, which has different mechanical and histological properties from elastic cartilage. In our efforts to develop foundational technologies for joint Hyaline cartilage repair and reconstruction, we conducted this study to obtain an answer to this question. We created an experimental canine model of knee joint cartilage damage, transplanted ear-derived autologous cartilage progenitor cells. The reconstructed cartilage was rich in proteoglycans and showed unique histological characteristics similar to joint Hyaline cartilage. In addition, mechanical properties of the reconstructed tissues were higher than those of ear cartilage and equal to those of joint Hyaline cartilage. This study suggested that joint Hyaline cartilage was reconstructed from ear-derived cartilage progenitor cells. It also demonstrated that ear-derived cartilage progenitor cells, which can be harvested by a minimally invasive method, would be useful for reconstructing joint Hyaline cartilage in patients with degenerative arthropathies.
David R Mcclay - One of the best experts on this subject based on the ideXlab platform.
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a molecular analysis of Hyalin a substrate for cell adhesion in the Hyaline layer of the sea urchin embryo
Developmental Biology, 1998Co-Authors: Gary M Wessel, Linnea Berg, David L Adelson, Gail Cannon, David R McclayAbstract:Abstract The Hyaline layer of echinoderm embryos is an extraembryonic matrix that functions as a substrate for cell adhesion through early development. The major constituent of the Hyaline layer is the protein Hyalin, a fibrillar glycoprotein of approximately 330 kDa that multimerizes in the presence of calcium. Here we provide a molecular characterization of Hyalin and identify a region of the protein that is important for its function in cell adhesion. Partial Hyalin cDNAs were identified from two sea urchin species, Strongylocentrotus purpuratus and Lytechinus variegatus, by screening expression libraries with monoclonal antibodies to Hyalin. The cDNAs each encode a tandemly arranged series of conserved repeats averaging 84 amino acids. These Hyalin repeats are as similar between the two species as they are to repeats within each species, suggesting a strong functional conservation. Analysis of this repeat shows that it is a unique sequence within the GenBank database with only weak similarity to mucoid protein sequences. The Hyalin mRNA is approximately 12 kb in length and is present in developing oocytes coincident with the appearance of cortical granules, the vesicle in which the Hyalin protein is specifically packaged. The mRNA is present throughout oogenesis but is rapidly lost at oocyte maturation so that eggs and early embryos have no detectable Hyalin mRNA. The Hyalin protein, however, remains at relatively constant levels throughout development. Thus, all the Hyalin protein present during early development, when no RNA is detectable, is maternally derived and exocytosed from cortical granules at fertilization. Hyalin mRNA reaccumulates in embryos beginning at the mesenchyme blastula stage; a RNA gel blot and in situ hybridization analysis of gastrulae and larvae shows a progressive confinement of Hyalin mRNA to the aboral ectoderm. Recombinant Hyalin containing the tandem repeat region of the protein was expressed in bacteria and is shown to serve as an adhesive substrate, almost equal to that of native Hyalin, in cell adhesion assays. This adhesive activity is partially blocked by dilute Hyalin monoclonal antibody Tg-HYL to the same extent as that for native Hyalin. Thus, this Hyalin repeat region appears to contain the ligand for the Hyalin cell surface receptor. These data help explain some of the classic functions ascribed to the Hyalin protein in early development and now enable investigators to focus on the mechanisms of cell interactions with the Hyaline layer.
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on the ultrastructure of Hyalin a cell adhesion protein of the sea urchin embryo extracellular matrix
Journal of Cell Biology, 1992Co-Authors: David L Adelson, Mark C Alliegro, David R McclayAbstract:Hyalin is a large (ca. 350 x 10(3) kD by gel electrophoresis) molecule that contributes to the Hyalin layer surrounding the sea urchin embryo. In previous work a mAb (McA Tg-HYL), specific for Hyalin, was found to inhibit cell-Hyalin adhesion and block morphogenesis of whole embryos (Adelson, D. L., and T. D. Humphreys. 1988. Development. 104:391-402). In this report, Hyalin ultrastructure was examined via rotary shadowing. Hyalin appeared to be a filamentous molecule approximately 75-nm long with a globular "head" about 12 nm in diameter that tended to form aggregates by associating head to head. Hyalin molecules tended to associate with a distinct high molecular weight globular particle ("core"). In fractions containing the core particle often more than one Hyalin molecule were seen to be associated with the core. The core particle maintained a tenacious association with Hyalin throughout purification procedures. The site(s) of McA Tg-HYL binding to the Hyalin molecule were visualized by decorating purified Hyalin with the antibody and then rotary shadowing the complex. In these experiments, McA Tg-HYL attached to the Hyalin filament near the head region in a pattern suggesting that more than one antibody binding site exists on the Hyalin filament. From the ultrastructural data and from the cell adhesion data presented earlier we conclude that Hyalin is a filamentous molecule that binds to other Hyalin molecules and contains multiple cell binding sites. Attempts were made to demonstrate the existence of lower molecular weight Hyalin precursors. Whilst no such precursors could be identified by immunoprecipitation of in vivo labeled embryo lysates, immunoprecipitation of in vitro translation products suggested such precursors (ca 40 x 10(3) kD) might exist.