Charles Prince

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Osteopontin is a phosphorylated bone matrix sialoprotein, postulated to play a regulatory role in biomineralization. The effects of a crude preparation of rat bone osteopontin and a more highly purified bovine bone osteopontin were evaluated using a gel diffusion system to measure effects of 0.1-100 micrograms/ml of this matrix protein on hydroxyapatite(More)
Newly synthesized proteoglycans of rat incisors were labelled in vivo for 6h with [35S]-sulphate in order to facilitate their detection during purification and characterization. Proteoglycans were extracted from non-mineralized portions (predentine) of rat incisors with 4M-guanidinium chloride and subsequently from dentine by demineralization with a(More)
Type beta transforming growth factor (TGF beta) was shown to regulate the production of several extracellular matrix proteins. Osteopontin (OP) is a recently discovered bone matrix protein which was shown to promote the attachment of osteoblastic rat osteosarcoma ROS 17/2.8 cells to their substrate. We examined the effects of TGF beta on OP production and(More)
Osteopontin (OPN), an extracellular matrix cell adhesion protein, was found to serve as a substrate for the incorporation of radiolabelled putrescine mediated by a commercial preparation of guinea pig liver transglutaminase. Preliminary evidence also suggests that OPN serves as a substrate for the plasma transglutaminase, Factor XIIIa. While the protein(More)
Polyclonal antibodies against a 44-KD phosphoprotein (44K BPP) from rat bone were raised in rabbits, affinity-purified, and used as probes to study the protein's distribution in various types of developing bones from newborn rats. Three immunostaining procedures were applied utilizing indirect immunofluorescence, avidin-biotin-peroxidase complex, and(More)
A phosphorylated glycoprotein was purified from the mixture of proteins extracted by demineralization of rat bone with 0.5 M EDTA in 4 M guanidinium chloride. A high level of purity for the preparation was indicated by a single band on sodium dodecyl sulfate (SDS)-gradient gel electrophoresis, sedimentation equilibrium ultracentrifugal data, and by(More)
Bone gamma-carboxyglutamic acid (Gla)-containing protein (BGP or osteocalcin) and 44 kDa bone phosphoprotein (44K BPP, also called Sialoprotein I or osteopontin) have been localized at the ultrastructural level in osteoblasts from woven bones of newborn rats. Frozen, undecalcified sections of periodate-lysine-paraformaldehyde fixed specimens were incubated(More)
The extracellular matrix of the normal adult brain lacks expression of most of the adhesive glycoproteins that are known to promote cell attachment, and it has been thought that the malignant invasion of astrocytoma tumor is mediated primarily by remodeling of the matrix by the tumor cells. It has been reported, however, that normal brain neuropil does(More)
We investigated the effects of 1,25-dihydroxyvitamin D3 on the synthesis of osteopontin, a phosphorylated cell attachment glycoprotein, in ROS 17/2.8 cells, a clonal osteoblast-like rat osteosarcoma cell line. We observed a dose dependent increase in uptake of [32PO4] into osteopontin secreted into the medium. An increased incorporation of [35S]-methionine(More)
Previous immunohistochemical data have shown that the 44-kDal bone phosphoprotein (44K BPP, also called sialoprotein I or oestopontin) recently isolated in our laboratory was synthesized by osteoblasts and osteocytes and was expressed early during differentiation of boneforming cells. We report here the presence of 44K BPP antigenicity at certain ectopic(More)