[Molecular mechanisms for signal-transmission of mechanical stress into bone-forming cells]

One function of bone in organism is to mechanically support the body. The bone is always exposed to mechanical stress such as gravity and locomotion, and the shape of bone is adapted to the mechanical loading. Mechanical loading on bone generates extracellular deformation and fluid flow, and the mechanical stimuli are translated to mechanical signals such as mechanical strain and fluid shear stress. Bone-forming cells such as osteocytes and osteoblasts are mechanosensors. When these cells receive the mechanical stress, they stimulate the production of local regulators for bone metabolism such as prostaglandins, and various growth factors and cytokines. By the actions of these factors on bone-forming cells and bone-resorbing cells in bone microenvironment, the bone metabolism is turn over in conformity with the mechanical stress.