Osteoclasts are specialized macrophages that resorb bone. Mice lacking the AP-1
component c-Fos are osteopetrotic because of a lack of osteoclast differentiation and show
an increased number of macrophages. The nature of the critical function of c-Fos in
osteoclast differentiation is not known. Microarray analysis revealed that Nfatc1, another key
regulator of osteoclastogenesis, was down-regulated in Fos-/-osteoclast precursors.
Chromatin immunoprecipitation assay showed that c-Fos bound to the Nfatc1 and Acp5 …