The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) rapidly blocks the terminal differentiation of normal cul tured Chondroblasts. In TPA, the chondroblasts lose their char acteristic polygonal morphology and initiate the synthesis of an atypical type IV sulfated proteoglycan. This atypical proteoglycan has lower molecular size, shorter polysaccharide chains, and different 4S-disaccha...

We have isolated a unique, basement membrane proteoglycan from the Engelbreth-Holm-Swarm (EHS) sarcoma. This proteoglycan, estimated to be 0.75 X 10(6) daltons, was found to contain about equal amounts of protein and covalently linked heparan sulfate. Antibody prepared against this proteoglycan reacts with the basement membrane matrix in the tumor and with the basement membranes in skin, kidney...

Proteoglycan was isolated from cartilage and freed from contaminating glycoproteins and hyaluronic acid. The macromolecule consists of a protein core covalently linked to a number of glycosaminoglycan side chains, namely chondroitin sulphate and keratan sulphate. This proteoglycan retards the attachment of a variety of cell types to tissue culture plastic and to collagen. Glycosaminoglycans alo...

Murine recombinant interleukin 1 (IL1) was tested for its ability to affect intact murine articular cartilage. IL1 caused enhanced proteoglycan degradation and severe inhibition of chondrocyte synthetic function at a concentration of 3 U/ml (100 pg/ml). Inhibition of proteoglycan synthesis appeared to be delayed in onset but occurred consistently after 24 hours. Pulse chase experiments made it ...

The IGF-I (insulin-like growth factor-I) signalling pathway responsible for regulation of proteoglycan synthesis in chondrocytes has not been defined and is the focus of the present study. Chondrocytes isolated from normal human articular cartilage were stimulated with IGF-I in monolayer culture or in suspension in alginate. IGF-I activated members of both the PI3K (phosphoinositide 3-kinase) p...

The effects of treatment of purified neonatal human articular-cartilage proteoglycan aggregate with H2O2 were studied. (1) Exposure of proteoglycan aggregate to H2O2 resulted in depolymerization of the aggregate and modification of the core protein of both the proteoglycan subunits and the link proteins. (2) Treatment of the proteoglycan aggregate with H2O2 rendered the proteoglycan subunits un...

Bovine nasal cartilage was studied by electron microscopy before and after extraction with 4 M guanidinium chloride or 1.9 M CaCl(2). These solvents removed matrix granules, basophilia, and 85% of the proteoglycan complex, measured as hexuronate. Simultaneously, many collagen fibrils were disaggregated into component microfibrils (approximately 40 A thick). In contrast to the above solvents, ex...

This article explores possible mechanisms governing extracellular matrix deposition in engineered cartilaginous cell pellets. A theoretical investigation is carried out alongside an experimental study measuring proteoglycan and collagen volume fractions within murine chondrogenic (ATDC-5) cell pellets. The simple mathematical model, which adopts a nutrient-dependent proteoglycan production rate...

Two pools of heparan sulfate proteoglycans have been selectively solubilized from rat liver plasma membranes by successive incubations with heparin and detergent. The two populations of proteoglycans have similar polyanionic properties as indicated by identical elution positions on ion-exchange chromatography on DEAE-Sephacel but differ in buoyant density in CsCl when analyzed by density gradie...

Cartilage proteoglycan is thought to be composed of subunits, core proteins with covalently attached sulphated polysaccharide side chains, which form aggregates by non-covalent association with a link protein. The new technique of non-disruptive extraction followed by fractionation in caesium chloride gradients provides a useful means of preparing relatively pure proteoglycan aggregate, subunit...