Osteocyte function under compressive mechanical force

SummaryMechanical stress is an essential factor for physiological response and maintaining homeostasis of living bodies. Bone changes its molphology and density in response to the physical circumstances such as mechanical stress. Bone tissue remodeling is regulated by the cells in bone: osteoblasts, osteoclasts and their progenitors. Recently, osteocytes terminally differentiated from osteoblasts have been considered to play significant role in bone remodeling and act as mechanosensitive cells. We have previously demonstrated that osteocytes early respond to mechanical compressive force and produce osteopontin to act as mechanotransducers, which induce bone resorption in the experimental tooth movement model. Meanwhile, we also found that CCN2/CTGF expression, hereby apoptosis is induced in osteocytes in response to compressive mechanical stress triggering bone resorption. These results indicate that osteocytes are the major mechanosensitive cells in bone tissues and involved in regulation of osteoclastic bone resorption. In this review, I would like to describe the action of compressive mechanical stress in osteocytes and discusse the molecular and cellular mechanisms of mechanosensing and mechanotransduction leading to the induction of osteocyte apoptosis and thereafter, to the increase of bone resorption.