[The regulation of osteoclastogenesis by IFN]

Bone homeostasis is maintained by the balanced activities of two bone specific cell types: bone-resorbing osteoclasts and bone-forming osteoblasts. Since the disorder of osteoclast differentiation and/or activity leads to bone diseases such as postmenopausal osteoporosis, rheumatoid arthritis, etc., it is central to identify factors that regulate osteoclastogenesis and to study the regulatory mechanisms. Here, we show IFNs (IFN-beta and IFN-gamma) as new regulators of osteoclastogenesis: each IFN inhibits osteoclastogenesis via different molecular mechanisms. We also show the regulation of osteoblastogenesis by Stat1, an essential transcription factor for IFN signal. Our research will shed light on the novel cross-talk between IFN signals and bone cells (Table 1).