Ketoconazole and phorbol myristate acetate regulate osteoclast precursor fusion in primary murine marrow culture
✍ Scribed by Xian Fan; Diane M. Biskobing; Steven Bain; Dr. Janet Rubin
- Book ID
- 102875504
- Publisher
- American Society for Bone and Mineral Research
- Year
- 2009
- Tongue
- English
- Weight
- 887 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0884-0431
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✦ Synopsis
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 D~3~ (1,25(OH)~2~D~3~). 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 μM) 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.