Taurine exerts anti-osteoclastogenesis activity via inhibiting ROS generation, JNK phosphorylation and COX-2 expression in RAW264.7 cells

Taurine is one of the abundant amino acids present in mammalian cells. It exerts various physiological actions such as wound healing, radioprotection, neuroprotection and anti-anxiety. In the present study, we sought to determine if taurine could inhibit osteoclastogenesis and explore the potential role of cyclooxygenase-2 (COX-2) and Jun N-terminal kinase (JNK) with reactive oxygen species (ROS). The level of intracellular ROS generated by lipopolysaccharide (LPS) was measured with DCFH-DA staining and fluorescence microscopic analysis was also performed in response to taurine in RAW264.7 cells. The expression of COX-2 and phosphorylation status of JNK by LPS was analyzed by Western blot analysis in the presence of taurine. Osteoclastogenesis was induced by LPS in the absence or presence of taurine and TRAP assay was performed to confirm the formation of osteoclast cells. ROS production was significantly enhanced by LPS and taurine treatment inhibited the ROS generation in a dose-dependent manner. The fluorescence microscopic analysis clearly showed the inhibition of ROS staining by taurine. Western blot analysis indicated that taurine significantly inhibited LPS induced COX-2 protein expression and it also inhibited phosphorylation of JNK. Taurine at the same concentration inhibited osteoclastogenesis induced by LPS, suggesting that taurine prevent osteoclast differentiation by inhibiting ROS generation. Inhibition of COX-2 expression and JNK phoshorylation could be an important mechanism by which taurine exerts anti-osteoclastogeneis.