Mechanisms of bone anabolic action by PTH

: Many researchers have been investigated the mechanisms of bone anabolic action by PTH through various approaches. For example, an increase in the number of osteoblasts at early differentiation stage, anti-apoptotic actions, an involvement of growth factors, such as insulin-like growth factor (IGF) - I, and Runx2 are included in them. Recent accumulating evidence suggest the involvement of canonical Wnt-β-catenin signaling in PTH actions. Recent studies have noticed the role of osteocytes in bone anabolic action by PTH, in contrary to the previous concept. We recently identified Tmem119 as an osteoblast differentiation factor, which is related to increases in Smad3 andβ-catenin levels by PTH in osteoblasts.