Molecular Mechanism of Ginsenoside Rg3 Alleviation in Osteoporosis via Modulation of KPNA2 and the NF-κB Signalling Pathway

Osteoporosis is mainly caused by an imbalance in osteoclast and osteoblast regulation, resulting in an imbalance in bone homeostasis. Ginsenoside Rg3 (Rg3) has been reported to have a therapeutic effect on alleviating osteoporosis. Nonetheless, the underlying mechanisms have not been completely elucidated. Herein, the molecular mechanism of Rg3 alleviation in osteoporosis was further explored. An in vitro model was established utilising the receptor activator of nuclear factor-kappaB ligand (RANKL) to induce osteoclast differentiation of RAW264.7 cells. RNA-sequencing results showed that karyopherin subunit alpha 2 (KPNA2) is one of the significantly differentially expressed genes regulated by Rg3 in RANKL-induced RAW264.7 cells. Basic experiments further suggested that KPNA2 is up-regulated in a time-dependent manner in the RANKL-induced RAW264.7 cells, while Rg3 treatment reduced its expression in a dose- and time-dependent manner. Knockdown of KPNA2 inhibited osteoclast formation and the expression of related molecules, including those in the nuclear factor kappa-B (NF-κB) pathway. The NF-κB inhibitor, JSH-23, partially abolished the impact of KPNA2 overexpression on osteoclast formation, indicating KPNA2 activates NF-κB. Furthermore, KPNA2 overexpression partially abolished the inhibitory impact of Rg3 on osteoclast formation, indicating that KPNA2 is a target of Rg3. These results suggest that KPNA2 plays a role in how Rg3 influences on osteoclast differentiation and osteoporosis through the NF-κB pathway.