Active caspase-3 is required for osteoclast differentiation
Based on our earlier observation that caspase-3 is present in osteoclasts that are not undergoing apoptosis, we investigated the role of this protein in the differentiation of primary osteoclasts and RAW264.7 cells (Szymczyk KH, et al, 2005, Caspase-3 activity is necessary for RANKL-induced osteoclast differentiation. The Proceedings of the 8th ICCBMT). We noted that osteoclast numbers are decreased in long bones of procaspase-3 knockout mice and that receptor activator of NF-ÎºB ligand (RANKL) does not promote differentiation of isolated preosteoclasts. In addition, after treatment with inhibitors of caspase-3 activity, neither the wild-type primary nor the RAW264.7 cells express TRAP or became multinucleated. We found that immediately following RANKL treatment, procaspase-3 is cleaved and the activated protein is localized to lipid regions of the plasma membrane and the cytosol. We developed RAW264.7 procaspase-3 knockdown clonal cell lines using RNAi technology. Again, treatment with RANKL fails to induce TRAP activity or multinucleation. Finally, we evaluated NF-ÎºB in procaspase-3 silenced cells. We found that RANKL treatment prevented activation and nuclear translocation of NF-ÎºB. Together these findings provide direct support for the hypothesis that caspase-3 activity is required for osteoclast differentiation. Â© 2006 Wiley-Liss, Inc.
Journal of cellular physiology
Szymczyk, K. H.; Freeman, T. A.; Adams, Christopher S.; Srinivas, V.; and Steinbeck, M. J., "Active caspase-3 is required for osteoclast differentiation" (2006). PCOM Scholarly Papers. 1588.