Abstract
During bone resorption, osteoclasts are exposed to high Ca2+ concentrations (up to 40 mM). The role of high extracellular Ca2+ in receptor activator of NF-kappaB ligand (RANKL)-mediated osteoclast survival and their functional interrelationship is unclear. in this study, we show that RANKL enhances osteoclast tolerance to high extracellular Ca2+ by protecting the cell from cell death in a dose dependent manner. We have provided evidence that RANKL does this by attenuating high extracellular Ca2+- induced Ca2+ elevations. Moreover, we have found that high extracellular Ca2+- induced cell death was partially inhibited by a caspase-3 inhibitor, suggesting caspase-3-mediated apoptosis is involved. Conversely, using reporter gene assays and Western blot analysis, we have demonstrated that high extracellular Ca2+ desensitizes the RANKL-induced activation of NF-kappaB and c-Jun N-terminal kinase (JNK), and inhibits constitutive and RANKL-stimulated ERK phosphorylation, indicating a negative feed-back mechanism via specific RANKL signaling pathways. Taken together, this study provides evidence for a reciprocal regulation between high extracellular Ca2+ and RANKL signaling in RAW cell derived osteoclasts. Our data imply across talk mechanism of extracellular Ca2+ on osteoclast survival through the regulation of RANKL. (C) 2004 Wiley-Liss, Inc.
Original language | English |
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Pages (from-to) | 554-562 |
Journal | Journal of Cellular Physiology |
Volume | 202 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2005 |