Research progress of signaling pathways in osteoporosis

Osteoporosis is a systemic metabolic degenerative skeletal disease, characterized by reduced bone mass and disrupted bone microarchitecture, leading to enhanced bone fragility, decreased bone strength and increased susceptibility to fractures. Its occurrence and development is an extremely complex biological process, which is a multi factor, multi gene and multi stage experience. Osteoporosis is the fourth chronic disease in our country, which mainly affects postmenopausal women and the elderly. Bone mass is jointly maintained by the action of bone resorption by osteoclasts and bone formation by osteoblasts. If the imbalance between the two occurs, resulting in reduced bone formation and increased bone resorption, bone homeostasis is changed to cause osteoporosis. Traditional treatment for osteoporosis are drugs which just to depress bone resorption (such as bisphosphonates and estrogen), or just to promote bone formation (such as PTH and statins), or just to supply the source of calcium. This single point of local treatment is clearly difficult to play a long-term part in complex lesions of osteoporosis. In recent years, researchers have studied the molecular signaling pathways related to osteoporosis. The current studies reveal that signaling pathways in osteoporosis include MAPK, PI3K/Akt, Wnt/β-catenin, RANKL/RANK/OPG, Hedgehog and Notch signaling pathways. These signaling pathways play an important role in the molecular pathogenesis of osteoporosis. In addition, there are GH/IGF-1, PPAR-γ, PTH signaling pathways and so on. Taking these signaling pathways as targeting points is a new strategy for the development of new anti osteoporosis drugs or the prevention of osteoporosis. But there are cross-talks and/or interactions between these signaling pathways related to osteoporosis and the pathogenesis of osteoporosiswhich make its therapy more difficult. This paper reviews the research progress of signaling pathway in osteoporosis in order to explore the molecular mechanism of its occurrence. Thus these signaling pathways can be taken as new targets to develop safer and more effective anti-osteoporosis drugs.