Bone morphogenetic proteins: Relationship between molecular structure and their osteogenic activity

Bone morphogenetic proteins (BMPs) are a family of potent, multifunctional growth factors belonging to transforming growth factor-β (TGF-β). They are highly conservative in structures. Over 20 members of BMPs with varying functions such as embryogenesis, skeletal formation, hematopoiesis and neurogenesis have been identified in human body. BMPs are unique growth factors that can induce the formation of bone tissue individually. BMPs can induce the differentiation of bone marrow mesenchymal stem cells into osteoblastic lineage and promote the proliferation of osteoblasts and chondrocytes. BMPs stimulate the target cells by specific membrane-bound receptors and signal transduced through mothers against decapentaplegic (Smads) and mitogen activated protein kinase (MAPK) pathways. It has been demonstrated that BMP-2, BMP-4, BMP-6, BMP-7, and BMP-9 play an important role in bone formation. This article focuses on the molecular characterization of BMPs family members, mechanism of osteogenesis promotion, related signal pathways of osteogenic function, relationships between structure and osteogenetic activity, and the interactions among family members at bone formation.