c‐myc Is Required for Osteoclast Differentiation

• Published in: Journal of bone and mineral research 2002-05, Vol.17 (5), p.763-773
• Main Authors: Battaglino, R., Kim, D., Fu, J., Vaage, B., Fu, X‐Y., Stashenko, P.
• Format: Article
• Language: English
• Subjects: Animals; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Basic-Leucine Zipper Transcription Factors; Biological and medical sciences; bone formation; c-Myc gene; Carrier Proteins - pharmacology; Cell Differentiation - drug effects; Cell Line; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression - drug effects; Genes, myc - drug effects; Membrane Glycoproteins - pharmacology; Mice; Monocytes - cytology; Monocytes - drug effects; Monocytes - metabolism; myc; osteoclast differentiation; Osteoclasts - cytology; Osteoclasts - drug effects; Osteoclasts - metabolism; Osteogenesis - drug effects; Osteogenesis - physiology; Proteins - genetics; Proteins - metabolism; Proto-Oncogene Proteins c-myc - metabolism; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Repressor Proteins; Skeleton and joints; TNF Receptor-Associated Factor 6; TRANCE protein; Transcription Factors; Transfection; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.2002.17.5.763

The role of the receptor activator of nuclear factor κB (NF‐κB) ligand (RANKL)—a tumor necrosis factor (TNF)‐related cytokine—in osteoclast formation has been established clearly. However, the downstream signaling pathways activated by this cytokine remain largely unknown. To identify genes that play a role in osteoclastogenesis, we used RAW 264.7 mouse monocytes as a model system for the differentiation of multinucleated osteoclasts from mononucleated precursors. RAW 264.7 cells were induced with RANKL to form multinucleated giant osteoclast‐like cells (OCLs) that expressed a number of osteoclast‐specific markers and were able to form resorption pits on both calcium phosphate films and bone slices. This system was used to identify genes that are regulated by RANKL and may play a role in osteoclast differentiation. The proto‐oncogene c‐myc was strongly up‐regulated in RANKL‐induced OCLs but was absent in undifferentiated cells. Expression of Myc partners Max and Mad, on the other hand, was constant during OCL differentiation. We expressed a dominant negative Myc in RAW 264.7 cells and were able to block RANKL‐induced OCL formation. Northern Blot analysis revealed a delay and a significant reduction in the level of messenger RNA (mRNA) for tartrate‐resistant acid phosphatase (TRAP) and cathepsin K. We conclude that c‐myc is a downstream target of RANKL and its expression is required for RANKL‐induced osteoclastogenesis.