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Biomedical subjects

A Noro

Publications and source records attributed to A Noro.

32 records · Page 2Linked to original sources
PubMed1988

Interaction of tissue-type plasminogen activator and plasminogen activator inhibitor 1 on the surface of endothelial cells.

The site of the reaction between plasminogen activators and plasminogen activator inhibitor 1 (PAI-1) was investigated in cultures of human umbilical vein endothelial cells. In conditioned medium from endothelial cells, two forms of a plasminogen activator-specific inhibitor can be demonstrated: an active form that readily binds to and inhibits plasminogen activators and an immunologically related quiescent form which has no anti-activator activity but which can be activated by denaturation. In conditioned medium, only a few percent of PAI-1 is the active form. However, the addition of increasing concentrations of tissue-type plasminogen activator (t-PA) or urokinase to confluent endothelial cells produced a saturable (3.0 pmol/5 x 10(5) cells), dose-dependent increase of the activator-PAI-1 complex in the conditioned medium even in the presence of actinomycin D or cycloheximide. This resulted also in a dose-dependent decrease of the residual PAI activity measured by reverse fibrin autography both in the conditioned medium and cell extracts. Short-time exposure of endothelial cells to a large amount of t-PA caused almost complete depletion of all cell-associated PAI activity. Although there was no detectable PAI activity even after activation of PAI by denaturants or antigen in the culture medium at 4 degrees C without the addition of t-PA, the addition of t-PA at 4 degrees C not only resulted in the formation of 70% of the amount of the t-PA.PAI complex in conditioned medium at 37 degrees C, but also induced PAI-1 antigen in a time and dose-dependent manner in the conditioned medium. Moreover, 125I-labeled t-PA immobilized on Sepharose added directly to endothelial cells formed a complex with PAI-1 in a dose-dependent manner. On the other hand, no detectable complex was formed with PAI-1 when Sepharose-immobilized 125I-labeled t-PA was added to endothelial cells under conditions in which the added t-PA could not contact the cells directly but other proteins could pass freely by the use of a Transwell. All these results suggest that a "storage pool" on the surface of endothelial cells or the extracellular matrix produced by endothelial cells contains almost all the active PAI-1, and reaction between PA and PAI-1 mainly occurs on the endothelial cell membranes, resulting in a decrease of the conversion of active PAI-1 to the quiescent form.

Dose-Response Relationship, Drug↗
PubMed1983

The occurrence of three different proteoglycan species in chick embryo cartilage. Isolation and characterization of a second proteoglycan (PG-Lb) and its precursor form.

Three different molecular species of proteoglycan (designated PG-H, PG-Lb, and PG-Lt) have been isolated from chick embryo epiphyseal cartilage. PG-H is a major proteoglycan of the tissue and identical, or nearly identical, with so-called cartilage-characteristic proteoglycan previously described in mammalian and avian cartilages. The third proteoglycan, PG-Lt, differs from the other two in containing disulfide-bonded collagenous polypeptides (Noro, A., Kimata, K., Oike, Y., Shinomura, T., Maeda, N., Yano, S., Takahashi, N., and Suzuki, S. (1983) J. Biol. Chem. 258, 9323-9331). The second proteoglycan, PG-Lb, consists of a core protein with Mr congruent to 52,000 dermatan sulfate copolymer chains with glucuronic acid/iduronic acid residues. Upon chondroitinase ABC digestion, the proteoglycan yields a protein-enriched core fraction of Mr congruent to 43,000. Its amino acid composition, tryptic peptide profile, and immunochemical properties indicate that PG-Lb is distinctly different from PG-H and PG-Lt in core protein structure. PG-Lb shows no specific binding with hyaluronic acid. Pulse-chase experiments with [3H]serine indicate that PG-Lb is first synthesized as a precursor form (pro-PG-Lb) that can be distinguished from PG-Lb by the production of a core molecule of Mr congruent to 52,000 after chondroitinase ABC digestion. This core molecule is labeled when [2-3H]mannose is used as a precursor, suggesting that it contains a glycoprotein type oligosaccharide. Since the core molecule from pro-PG-Lb is significantly larger in molecular weight than that from PG-Lb, the conversion of pro-PG-Lb to PG-Lb should involve scission of the polypeptide or possibly removal of mannose-containing oligosaccharide chain.

Amino Acids↗
PubMed1983

Isolation and characterization of a third proteoglycan (PG-Lt) from chick embryo cartilage which contains disulfide-bonded collagenous polypeptide.

Chick embryo epiphyseal cartilage has been shown to contain three different proteoglycan species (PG-H, PG-Lb, and PG-Lt). This report is concerned with the purification and characterization of the third proteoglycan, PG-Lt. The proteoglycan can be separated from the other two by virtue of its low buoyant density in a CsCl density gradient and further purified by consecutive ion exchange and gel chromatography. The final preparation is composed of PG-Lt monomer and PG-Lt oligomer. The amino acid composition of PG-Lt is quite different from that of PG-H and PG-Lb and rather resembles that of collagens with respect to high content of glycine and high degrees of hydroxylation of proline and lysine. PG-Lt monomer is composed of disulfide-bonded subunits of Mr congruent to 120,000 and 190,000 as demonstrated by its gel electrophoretic behavior after reduction with 2-mercaptoethanol. The latter, but not the former, contains dermatan sulfate chains with glucuronic acid/iduronic acid residues and yields a protein-enriched core molecule of Mr congruent to 100,000 after digestion with chondroitinase ABC. Both of the protein subunits are completely digestible with bacterial collagenase. Immunofluorescence microscopic examination of cartilage tissues, using an antibody against PG-Lt, shows that this proteoglycan exists in both the cartilage matrix and perichondrial noncartilagenous region. When chondrocytes are plated onto tissue culture dishes, the antibody stains strands found on the cell surfaces and in the intercellular space of substrate-attached cell layers, suggesting that PG-Lt mediates cell-to-cell and cell-to-substrate contacts.

Amino Acids↗