Showing papers on "Osteopontin published in 1988"

Developmental expression of 2ar (osteopontin) and SPARC (osteonectin) RNA as revealed by in situ hybridization

Abstract: 2ar has been identified as a gene inducible by tumor promoters and growth factors in a variety of cultured mouse cell lines (Smith, J. H., and D. T. Denhardt. 1987. J. Cell. Biochem. 34:13-22). Sequence analysis shows that it codes for mouse osteopontin, an RGDS-containing, phosphorylated, sialic acid-rich Ca++-binding protein originally isolated from bone (Oldberg, A., A. Franzen, and D. Heinegard. 1986. Proc. Natl. Acad. Sci. USA. 83:8819-8823; Prince, C. W., T. Oosawa, W. T. Butler, M. Tomana, A. S. Brown, and R. E. Schrohenloer. 1987. J. Biol. Chem. 262:2900-3907.). In this paper we use Northern blot analysis and in situ hybridization to localize expression of 2ar during mouse embryogenesis. 2ar RNA is first detected in developing limb bones and calvaria at 14.5 d p.c., in a population of cells distinct from those expressing SPARC (osteonectin). High levels of 2ar expression are also seen in the bone marrow-derived granulated metrial gland cells of the deciduum and placenta, and in a number of epithelial tissues, including embryonic and postnatal kidney tubules, uterine epithelium and sensory epithelium of the embryonic ear. The temporal and spatial pattern of 2ar expression seen in vivo suggests that the protein plays a wider role than previously realized, in processes which are not confined to bone development.

44-kDal bone phosphoprotein (osteopontin) antigenicity at ectopic sites in newborn rats: kidney and nervous tissues.

Abstract: 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 sites, namely, the proximal-convoluted tubule of the kidney, neurons, sensory and secretory cells in the internal ear. To insure specificity and reproducibility, different immunohistochemical methods were used and affinity-purified antibodies against two separate preparations of pure 44K BPP were tested. In the cells of the proximal-convoluted tubule, 44K BPP immunoreactivity was observed within apical endocytotic vacuoles and within lysosomes. This staining thus correlates with the degradation of the 44K BPP epitope which we previously demonstrated to occur in serum. On the other hand, in the neurons of the acoustic ganglion and the sensory cells of the macula, 44K BPP immunoreactivity was associated with the Golgi apparatus indicating synthesis and secretion by these cells. The finding that the 44K BPP (or a structurally related molecule) is synthesized by neurons and neuroepithelial cells deserves further investigation with respect to a possible embryologie relationship between neuroectodermal cells and the precursors of some bone forming-cells of the skull.

Cell and molecular biology of vertebrate hard tissues

Abstract: Bone Development Factors Influencing the Expression of Dental Extracellular Matrix Biomineralization Stromal Stem Cells: Marrow-Derived Osteogenic Precursors Osteoblastic Differentiation Diversity of the Osteoblastic Phenotype The Regulation of Osteoclastic Development and Function Osteoclast Development: The Cell Surface and the Bone Environment Osteoclast Activity An Adhesion Variant of the MG- 63 Osteosarcoma Cell Line Displays an Osteoblast-Like Phenotype Expression of Type I Procollagen Genes Phosphoproteins from Teeth and Bone Non-Collagen Proteins in Bone Osteopontin: Structure and Biological Activity Polypeptide Growth Factors in Bone Matrix Hormonal Regulation of Bone Growth and Remodelling Cytokines Haemopoietic Growth Factors: Their Relevance in Osteoclast Formation and Function Clinical Implications Future Perspectives.

Non‐Collagen Proteins in Bone

Abstract: The non-collagen proteins of bone are a complex set of molecules that arise from local or exogenous sources. Because bone mineral is an excellent adsorbent, many circulatory and/or cell surface proteins bind to bone, where they may have immediate or subsequent effects. These include the alpha 2-HS-glycoprotein from blood and the potent growth factors TGF-beta, PDGF, IGF-1, FGF-a and -b, and IL-1, derived from both bone and non-bone cells. Furthermore, bone cell membrane proteins such as alkaline phosphatase may be cleaved from the cell surface and entrapped in the bone matrix. Bone is enriched in a variety of enzymes and their inhibitors by similar adsorption processes. Even osteocalcin, a bone cell product, is adsorbed to bone via mineral-binding (Gla) groups. The bone sialoproteins (BSP-I or osteopontin and BSP-II) also bind to the mineral via acidic groups. Because of this phenomenon it is difficult to distinguish whether a given protein's presence in bone is advantageous or merely fortuitous. The bone matrix proper consists of type I collagen and other osteoblast products such as osteonectin (a phosphorylated glycoprotein) and small proteoglycans (PG-I and/or PG-II) which are incorporated into bone collagen fibrils. These proteins may have additional roles in tissue morphogenesis and/or differentiation.