title: Ketoconazole and phorbol myristate acetate regulate osteoclast precursor fusion in primary murine marrow culture.
abstract: Osteoclast formation requires both precursor proliferation and then fusion into a multinuclear cell. These processes can be separated in primary murine marrow culture where osteoclastogenesis is stimulated by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Here we investigate the regulation of precursor fusion. Ketoconazole, an agent known to inhibit cell fusion, added during the fusion period (days 5-6), dose-dependently inhibited formation of tartrate-resistant acid phosphatase+ (TRAP+) multinucleated cells (TRAP+MNCs), maximally at 62 +/- 4% (n = 10). TRAP+MNCs in cultures exposed to 48 h of ketoconazole (1 microM) during fusion had fewer nuclei compared with control (11.7 +/- 0.6 vs. 15.1 +/- 0.9). This inhibitory effect was completely reversed 24 h after removal of ketoconazole from culture. Phorbol myristate acetate (PMA) stimulated TRAP+MNC formation when given during the last 12 h of culture (2.3 +/- 0.2 fold compared with control). This increased formation was unaffected by the addition of hydroxyurea and accompanied by an increase in nuclei per TRAP+MNC (15.5 +/- 0.9 vs. 13.1 +/- 0.6). Finally, staurosporine decreased TRAP+MNC formation in the presence or absence of PMA, implying that protein kinase C is involved in fusogenic processes. Regulation of fusion appears to be another mechanism by which bone remodeling can be modulated in vivo.
authors.affiliation: Department of Medicine, Veterans Affairs Medical Center, Atlanta, Georgia, USA.
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: D M
authors.initials: DM
authors.lastname: Biskobing
authors.forename: S
authors.initials: S
authors.lastname: Bain
authors.forename: J
authors.initials: J
authors.lastname: Rubin
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D000935:Antifungal Agents / Q000633:toxicity*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002459:Cell Fusion / Q000187:drug effects; D002478:Cells, Cultured; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015726:Giant Cells / Q000166:cytology / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism; D007654:Ketoconazole / Q000633:toxicity*; D051379:Mice; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects*; D019311:Staurosporine / Q000494:pharmacology; D000071681:Tartrate-Resistant Acid Phosphatase; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity*
chemical_list: D000935:Antifungal Agents; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D007654:Ketoconazole