Nrf2 is required for suppressing osteoclast RANKL-induced differentiation in RAW 264.7 cells via inactivating cannabinoid receptor type 2 with AM630.

OBJECTIVE

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is shown to as a negative-regulatory cause in osteoclasts differentiation. Cannabinoid receptor type 2 (CB2) is verified to regulate osteoclast differentiation, though with diversed results.

METHODS

In current research, we studied the Nrf2 role on osteoclast differentiation regulation with the CB2-selective agonists, AM1241, or CB2-selective antagonist, AM630, in RAW 264.7 macrophages. The nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation activator was confirmed by tartrate-resistant acid phosphatase (TRAP) staining as well as the TRAP activity analysis. In addition, Nrf2 siRNA was used to characterize the function of Nrf2 during osteoclast differentiation. We analyzed HO-1 and Nrf2 proteins levels with western blotting.

RESULTS

The results showed that AM1241 promoted, while AM630 suppressed, osteoclast differentiation in RAW 264.7 cells. Both AM1241 and AM630 increased the expressions of HO-1 and Nrf2. Nrf2 silencing promoted osteoclast differentiation and abolished the function of AM630 to inhibit osteoclast differentiation.

CONCLUSIONS

Our results suggested that Nrf2 was required for inhibiting osteoclast differentiation induced by RANKL of RAW 264.7 cells by AM630, which may provide the insights of a novel method to treat osteoclastogenic bone disease.