Selaginella tamariscina water extract inhibits receptor activator for the nuclear factor-κB ligand-induced osteoclast differentiation by blocking mitogen-activated protein kinase and NF-κB signaling.
BACKGROUND
Selaginella tamariscina has been traditionally used in Korea for treating hematochezia, hematuria, and prolapse of the anus. The aim of this study was to evaluate the inhibitory effect of Selaginella tamariscina water extract (ST-WE) on osteoclast differentiation, and to determine the underlying molecular mechanism.


METHODS
RAW264.7 cells were used as a model to examine receptor activator for the nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. Expression of osteoclastic genes and transcription factors was evaluated by real-time quantitative polymerase chain reaction (QPCR). Activation of the mitogen-activated protein kinases, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, and NF-κB were determined by Western blot analysis.


RESULTS
ST-WE significantly inhibited RANKL-induced tartrate-resistant acid phosphatase (TRAP) activity and formation of multinucleated osteoclasts in RAW264.7 cells. ST-WE also significantly inhibited the RANKL-induced mRNA expression of TRAP, cathepsin K, and the d2 isoform of vacuolar ATPase V(0) domain (ATPv0d2) gene. In addition, ST-WE inhibited the RANKL-induced phosphorylation of ERK, JNK, and p38, phosphorylation of I-κB(α) and NF-κB p65, and the expression of transcription factors c-fos, Fra-2, and nuclear factor of activated T cells 1. Furthermore, ST inhibited the bone resorptive activity of osteoclasts.


CONCLUSIONS
ST-WE might have beneficial effects on bonedisease by inhibiting osteoclastogenesis and osteoclastic activity.
KM-Based Herbal Drug Research Group, Korea Institute of Oriental Medicine, Daejeon 305-811, Republic of Korea.
Ki-Shuk
KS
Shim
Ju-Seop
JS
Kang
Min-Ho
MH
Lee
Jin Yeul
JY
Ma