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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 278 (1994), S. 265-271 
    ISSN: 1432-0878
    Keywords: Bone resorption ; Osteoclast ; Vacuolar H+-ATPase ; Immuno-electron microscopy ; Mouse (ddY)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract By means of light- and electron-microscopic immunocytochemistry, we have demonstrated the expression of vacuolar H+-ATPase in mouse osteoclasts. In fully differentiated osteoclasts, intense immunolabeling was observed along the plasma membranes including those of ruffled borders and associated pale vesicles and vacuoles, whereas those of clear zones and basolateral cell surfaces were entirely free of immunoreaction. Specific expression of vacuolar H+-ATPase was also detected over polyribosomes and cisterns of the rough-surfaced endoplasmic reticulum. Multinucleated osteoclastic cells were suspended on dentine slices and cultured for 48 h in the presence or absence of either concanamycin B or bafilomycin A1, specific inhibitors of vacuolar H+-ATPase. Morphometric analysis of co-cultured dentine slices with backscattered electron microscopy revealed that both inhibitors strongly reduced the formation of resorption lacunae in a dose-dependent manner. These results suggest that vacuolar H+-ATPase is produced in the rough-surfaced endoplasmic reticulum, stored in the membrane vesicles, and transported into the ruffled border membranes of osteoclasts, and that this enzyme plays a key role in the creation of an acidic subosteoclastic microenvironment for the demineralization of co-cultered substrates.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-5604
    Keywords: Key words: osteoclastogenesis ; osteoclast ; macrophage-colony stimulating factor ; osteoclast precursors ; osteoclast differentiation factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: We have isolated osteoclast precursors (OCPs) from cocultures of mouse calvarial cells and bone marrow cells without adding any osteotropic factors. OCPs expressed Mac-1, Mac-2, and Gr-1 antigens but not osteoclast markers such as tartrate-resistant acid phosphatase (TRAP) and calcitonin receptors, and they differentiated into TRAP-positive cells within 48 h on a fixed calvarial cell layer pretreated with osteotropic factors such as 1α,25-dihydroxyvitamin D3. In the present study, we investigated the regulatory mechanisms of OCP formation from hemopoietic cells and TRAP-positive cell formation from OCPs. Calvarial osteoblasts obtained from macrophage-colony stimulating factor (M-CSF) -deficient op/op mice failed to support OCP formation or the differentiation of OCPs into TRAP-positive cells. Both OCP formation and TRAP-positive cell formation supported by osteoblasts were completely inhibited by osteoclastogenesis inhibitory factor (OCIF, also called OPG), which is a decoy receptor of osteoclast differentiation factor (ODF; also called TRANCE, RANKL, and OPGL). When bone marrow cells were cultured for 4 days with soluble ODF (sODF/sRANKL) together with M-CSF, OCPs were formed even in the absence of osteoblasts. When OCPs were treated with sODF/sRANKL and M-CSF in the absence of osteoblasts, they differentiated into TRAP-positive cells within 48 h even in the presence of hydroxyurea. Northern blotting analysis revealed that osteoblasts constitutively expressed a certain level of ODF/RANKL mRNA. These results indicated that M-CSF and sODF/sRANKL produced by osteoblasts are two essential factors for both OCP formation and TRAP-positive osteoclast formation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0730-2312
    Keywords: Key words ; osteoclast ; focal adhesion kinase ; tyrosine kinase ; tyrosine phosphorylation ; podosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Involvement of tyrosine phosphorylation in osteoclastic bone resorption was examined using osteoclast-like multinucleated cells prepared from co-cultures of mouse osteoblastic cells and bone marrow cells in the presence of 1α,25-dihydroxyvitamin D3. When osteoclast-like cells were plated on culture dishes in the presence of 10% fetal bovine serum, they were sharply stained in their peripheral region by anti-phosphotyrosine antibody. Western blot analysis revealed that 115-to 130-kD proteins were tyrosine-phosphorylated in osteoclast-like cells. Using immunoprecipitation and immunoblotting, one of the proteins with 115-130 kD was identified as focal adhesion kinase (p125FAK), a tyrosine kinase, which is localized in focal adhesions. Immunostaining with anti-p 125FAK antibody revealed that p125FAK was mainly localized at the periphery of osteoclast-like cells. Herbimycin A, a tyrosine kinase inhibitor, not only suppressed tyrosine phosphorylation of p125FAK but also changed the intracellular localization of p125FAK and disrupted a ringed structure of F-actin-containing podosomes in osteoclast-like cells. Antisense oligodeoxynucleotides to p125FAK inhibited dentine resorption by osteoclast-like cells, whereas sense oligodeoxynucleotides did not. These results suggest that p125FAK is involved in osteoclastic bone resorption and that tyrosine phosphorylation of p125FAK is critical for regulating osteoclast function.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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